smartbook ch. 10

A uniform mixture of different substances is called a __________.

(homogeneous) solution

The charge on alkali metal ions is

+1

What ionic state are alkali metals?

+1

The charge on halogen ions is

-1

How many electrons are in the valence shell of group 1?

1

What group are the alkali metals?

1

The number of atoms in a molecule of Ca3(PO4)2 is

13

The halogens are in what Group on the periodic table?

17

Identify the missing number in the equation: ____C4H10 + 13O2 ---> 8CO2 + 10H20

2

The missing number in the equation 2HNO3 + Ca(OH)2 ---> Ca(NO3)2 + _______H2O

2

The missing number in the equation2HNO3+Ca(OH)2=Ca(NO3)2+( )H2O is

2

The chemical formula for the ionic compound K2S indicates that there is(are) _____ K+ ion(s) for every _____ S2- ion(s).

2; 1

The number of units of NaOH needed to react with 1 unit of H3PO4 to form Na3PO4 and H2O is

3

How many electrons are in the valence shell of halogens?

7

The missing number in the equation 6H3BO3 = H4B6O11 + ( )H2O is

7

The number of hydrogen atoms in a molecule of ammonium sulfide, (NH4)2S, is

8

What is a chemical equation?

A method used to express the results of a chemical change

Which of the following statements correctly defines the term molecule?

A molecule is an independent structure consisting of two or more atoms chemically bonded together.

Match the appropriate trend in activity with the illustration outlining how chemical activity varies in the periodic table. a. A, F b. B, C c. D d. E 1. Increasing Metallic Activity 2. Most active nonmetal 3. Increasing nonmetallic activity 4. Most Active Metal

A. 1 B. 3 C. 2 D. 4

Which of the following statements correctly characterizes the relationship between compounds and molecules?

All molecules are particles of compounds.

If Ca2+ is combined with two NO3- to form a polyatomic ion, the formula would look like ______.

Ca(NO3)2

Write the chemical formula for calcium chloride.

CaCl2

Which of the following cannot be broken down nor changed into simpler substances by chemical means?

Element

Which of the following nonmetals is most active?

F Fluorine has the greatest effective nuclear charge and will therefore be the most chemically active.

Which of the following nonmetals is the most active?

F (Fluorine has the greatest effective nuclear charge and will therefore be the most chemically active.)

Match the nonmetal with the anion it typically forms. a. F b. O c. N 1. -1 2. -2 3. -3

F: 1- O: 2- N: 3-

True or False: During a double displacement reaction, a single reactant is broken down into two or more products.

False

How do you write Iron (II) Chloride?

FeCl2

Order the following elements in terms of increasing activity, starting with the element that is the least active at the top of the list. Ga Ca K

Ga Ca K

Write the formula for potassium bromide.

KBr

What is the correct way to represent a compound that contains three magnesium atoms and two phosphate atom groups?

Mg3(PO4)2

Is the following equation balanced? PCl2 + 4H2O ---> H3PO4 + 5HCl

NO

The ion of the hydroxide group has the symbol

OH-

Pure Substance vs. Heterogeneous Substance

Pure Substance: A uniform material with definite composition and distinct properties Heterogeneous Substance: A material with variable composition whose components can be separated by physical means

A few elements form different ions depending on the chemical circumstance, and these are indicated by a ______.

Roman numeral to indicate the ionic charge

Which of the following atoms have a charge of +2 as an ion? (Select all that apply.) Sn Al Ca Zn Na

Sn (Sn can have a charge of +2 or +4) Ca Zn Not Al bc is has a charge of +3 as an ion. Not Na because it has a charge of +1 as an ion

Which type of material can be separated into different substances by boiling or freezing?

Solutions

Which of the following correctly defines the atomic mass of an element?

The average of the masses of that element's naturally occurring isotopes according to their abundance

Which of the following statements about electron transfer in ionic bond formation is true?

The number of electrons lost must equal the number of electrons gained by atoms when an ionic bond is formed.

Is water an element or a compound? Is calcium an element or a compound?

Water is a compound Calcium is an element

How does a heterogeneous substance differ from a pure substance? (Select all that apply.) a. The composition of a heterogeneous substance may vary. b. The components of a heterogeneous substance can be separated by physical means. c. A pure substance may only be heterogeneous. d. The components of a heterogeneous substance are chemically bonded together.

a & b

8. Which one or more of the following properties are characteristics of all metals? a. conducts electricity well b. conducts heat well c. is a solid at room temperature d. is transparent to light

a & b (conducts electricity well, conducts heat well)

Consider the formula for the ionic compound AlCl3. Which of the following statements correctly interpret this formula? (Select all that apply.) a. The positive ion in the compound is Al3+. b. The subscript 3 refers to the number of Al3+ ions in the formula. c. The compound contains 1 Al3+ ion for every 3 Cl- ions. d. The compound consists of AlCl3 molecules.

a & c

Which of the following statements correctly describe a chemical reaction? (Select all that apply.) a. The physical properties of the substance are changed during a chemical reaction. b. Only the physical form of the substance is changed during a chemical reaction. c. The molecular composition of the substance is altered during a chemical reaction. d. A chemical reaction involves a change in phase without a change in composition.

a & c

Which of the following are chemical characteristics shared by all halogens? (Select all that apply.) a. All halogens combine with hydrogen in the same way, and when the resulting compounds are dissolved in water, they produce an acidic solution. b. The halogens are relatively inactive elements. c. All halogens react with sodium to form compounds with the general formula Na2X, where X is a halogen. d. The halogens exist as F2, Cl2, Br2, and I2 at ordinary temperatures.

a & d

10. Which of the following is (are) true for active elements? a. they form compounds readily. b. they form stable compounds. c. they never occur as gases at room temperature. d. they liberate more heat when they react than inactive elements do.

a, b, & d they form compounds readily, they form stable compounds, & they liberate more heat when they react than inactive elements do.

Which of the following statements correctly describe Dalton's atomic theory? (Select all that apply.) a. Atoms of the same element are identical. b. All matter consists of atoms. c. Atoms combine randomly to form compounds. d. Compounds result from the specific combination of a specific ratio of atoms of different elements. e. Atoms of one element can be converted into atoms of another element.

a, b, d

Which of the following statements correctly describe the general characteristics of a covalent bond? (Select all that apply.) a. A covalent bond involves the sharing of electrons between two atoms. b. A covalent bond is typically observed when a metal bonds with a nonmetal. c. A covalent bond involves the attraction between the nucleus of each atom and the electrons of the other. d. A covalent bond can be formed through the sharing of more than one electron pair.

a, c d

Which statements correctly describe the relationship between the activity of an element and its resulting compounds? (Select all that apply.) a. The more active an element, the more stable the resulting compound. b. The more inactive an element, the more difficult it is to decompose its compounds. c. The more inactive an element, the easier it is to extract it from its ores. d. The more active an element, the more difficult it is to refine.

a, c, d b: The more inactive an element, the less stable its resulting compounds. An unstable compound is easier to decompose to its component elements.

Which of the following statements correctly describe the physical and chemical characteristics of alkali metals? (Select all that apply.) a. The alkali metals all react with hydroxide to produce compounds with the general formula XOH, where X is an alkali metal. b.. The alkali metals react with water to produce oxygen. c. The alkali metals are very active. d. The alkali metals combine with inactive nonmetals to form stable compounds. e. The alkali metals have low melting points.

a, c, e

Match each element with the correct family. a. Sodium b. Bromine c. Argon 1. Alkali Metal 2. Halogen 3. Inert Gas

a. 1 b. 2 c. 3

Match each substance involved in a chemical reaction with the correct definition. a. Reactant b. Product 1. Substance formed in a chemical reaction 2. Starting material in a chemical reaction

a. 2 b. 1

Match the type of element with the appropriate description of electron loss or gain by completing the sentence. a. Nonmetals b. Metals 1. ...tend to lose electrons when forming compounds 2. ... tend to gain or share electrons with other atoms when forming compounds.

a. 2 b. 1

Match each group in the periodic table with the correct name as indicated. a. Alkali Metals b. Halogens c. Inert (noble) gases Group 1 Group 7 Group 8

a. Alkali Metals: Group 1 b. Halogens: Group 7 c. Inert (noble) gases: Group 8

Compounds can be differentiated from solutions by comparing the proportions of their constituent elements by mass. Match the correct term with the correct description of elements by mass. a. Compounds b. Solutions 1. Always the same proportions of elements by mass 2. Can have a range of proportions of elements by mass

a. Compounds. 1. Always the same proportions of elements by mass b. Solutions. 2. Can have a range of proportions of elements by mass

Match each of the following types of element with the correct description. Instructions a. Metal b. Nonmetal c. Metalloid

a. Metal: An element that is a good conductor of electricity, has a shiny surface, and can be shaped b. Nonmetal: An element that is generally a gas, liquid, or a dull brittle solid at room temperature and is an insulator c. Metalloid: An element that has properties between those of metals and nonmetals

Which of the following formulas for ionic compounds are correct? (Select all that apply.) Use the attached table detailing the ions of some common elements in order to answer this question. a. Na2S b. Mg2O c. AlCl3 d. Ca2N3

a. Na2S c. Alcl3

Match the mixture with the appropriate designation. a. Steel b. Carbonated Soda 1. Heterogeneous Mixture 2. Homogeneous Mixture

a. Steel 2. Homogeneous Mixture b. Carbonated Soda 1. Heterogeneous Mixture

Which of the following mixtures are heterogeneous? (Select all that apply.) a. A cheese omelet b. Salt water c. Air d. Soil

a. a cheese omelet d. soil

20. Of the elements in group 8 of the periodic table, at room temperature and atmospheric pressure a.. are all gases b. are all liquids c. some are gases and the others liquids d. some are liquids and the others solids

a. all are gases

19. The elements in group 1 of the periodic table (except for hydrogen) are: a. all metals b. all nonmetals c. both metals and nonmetals d. neither metals nor nonmetals

a. all metals

26. An atom that loses its outer electron or electrons readily is a. an active metal b. an active nonmetal c. an inactive metal d. an inactive nonmetal

a. an active metal (active b/c it's getting rid of something to combine w/ something else, gives up electrons and becomes positively charged)

1. A pure substance that cannot be decomposed by chemical means is: a. an element b. a compound c. a solid d. a solution

a. an element

16. The place of an element in the periodic table is determined by its: a. atomic number b. atomic mass c. density d. chemical activity

a. atomic number

28. When a molecule breaks up into its constituent atoms, a. energy is absorbed b. energy is given off c. there is no energy charge d. any of these choices could be correct, depending on the molecule

a. energy is absorbed.

27. When they combine chemically with metal atoms, nonmetal atoms tend to a. gain electrons to become negative ions b. lose electrons to become positive ions c. remain electrically neutral d. do any of these, depending upon the circumstances

a. gain electrons to become negative ions

12. Of the following metals, the least active chemically is: a. gold b. aluminum c. iron d. sodium

a. gold (inactive, doesn't combine)

22. An alkali metal atom a. has one electron in its outer shell b. has two electrons in its outer shell c. has a filled outer shell d. lacks one electron of having a filled outer shell

a. has one electron in its outer shell (b/c it's in group 1)

The least active of the following elements is a. helium b. carbon c. chlorine d. oxygen

a. helium

7. The nonmetal whose chemical behavior is most like that of typical metals is: a. hydrogen b. helium c. chlorine d. carbon

a. hydrogen

Correctly complete the following sentences concerning the relative activity of elements and their resulting compounds. a. The more active an element... b. The more inactive an element... 1. ... the more difficult it is to decompose its compounds 2. ... the easier it is to refine from its ores

a1 b2

Match the type of element with the appropriate definition. a. Active Elements b. Inactive Elements 1. Readily combine to form compounds 2. Do not readily combine to form compounds

a1 b2

Transition metals include the rare-earth metals (lanthanides) and the ________.

actinides

The chemical reactivity of an element is designated as ________ if it readily combines to form compounds. If an element does not tend to react chemically, it is designated as ________.

active; inactive

The halogens are very ______ elements that all exist as molecules of two atoms at ordinary temperatures. The compounds formed when halogens react with ______ have similar chemical formulas.

active; metals

The alkali metals are ______ elements that tend to react with active ______ to produce stable compounds.

active; nonmetals

In a covalent compound

adjacent atoms share electron pairs

.What is the name of the group of elements in column 1 of the periodic table?

alkali metals

An atom whose outer electron shell is filled is

an inert gas

According to the periodic table, the chemical properties of the elements are periodic functions of their

atomic number

Dalton's atomic theory stated that matter consists of tiny indivisible particles called ________, which combine in fixed ratios to form __________.

atoms; compounds

The value for atomic mass reported in the periodic table for a given element is a(n) ____________ of the masses of that element's naturally occurring ____________ according to their abundance.

average; isotopes

What are the defining physical characteristics of halogens? (Select all that apply.) a. All gases at room temperature b. Brilliant colors c. Pungent odor d. Good conductors of electricity

b & c

Which of the following methods can be used to determine the relative activity of elements? (Select all that apply.) a. By comparing the boiling points of similar compounds b. By measuring the heat given off in similar chemical reactions c. By comparing the heat given off by decomposing similar compounds to their component elements d. By comparing the ability of similar compounds to conduct electricity

b & c

Which of the following options correctly describe different types of mixtures? (Select all that apply.) a. A heterogeneous mixture can be separated by physical means, whereas a homogeneous mixture cannot. b. Both homogeneous and heterogeneous mixtures may vary in composition. c. A mixture of substances that are in different phases is heterogeneous. d. The composition of a homogeneous mixture is the same throughout. e. A heterogeneous mixture is a mixture of more than two substances.

b, c, d

Which of the following are chemical characteristics shared by all halogens? (Select all that apply.) a. The halogens are relatively inactive elements. b. All halogens combine with hydrogen in the same way, and when the resulting compounds are dissolved in water, they produce an acidic solution. c. All halogens react with sodium to form compounds with the general formula Na2X, where X is a halogen. d. The halogens exist as F2, Cl2, Br2, and I2 at ordinary temperatures.

b, d

Which of the following statements correctly describe the trends in activity in the periodic table? (Select all that apply.) a. As we move from right to left in a period in the periodic table, metallic activity decreases. b. As we move down a group in the periodic table, activity of the elements tends to increase. c. The most active metal is fluorine. d. As we move from left to right in a period in the periodic table, nonmetallic activity increases.

b, d

3. The number of known elements is approximately: a. 50 b. 100 c. 200 d. 500

b. 100

14. At room temperature chlorine is: a. a colorless gas b. a greenish-yellow gas c. a reddish-brown liquid d. a steel-gray solid

b. a greenish-yellow gas

31. An element that can form an ionic compound with chlorine is a. carbon b. copper c. sulfur d. neon

b. copper (chlorine = nonmetal, need a metal to combine w/)

25. The most important factor in determining the chemical behavior of an atom is its: a. nuclear structure b. electron structure c. atomic mass d. solubility

b. electron structure

13. Of the following nonmetals, the most active chemically is: a. helium b. fluorine c. oxygen d. sulfur

b. fluorine (helium = inactive)

36. Chlorine forms Cl- ions. The compound FeCl3 is called: a. iron(I) chloride b. iron(III) chloride c. iron(I) chlorate d. iron(III) chlorate

b. iron(III) chloride

33. A compound whose name ends in -ate always contains a. hydrogen b. oxygen c. hydrogen and oxygen d. carbon

b. oxygen

5. Which of the following substances is a homogeneous mixture? a. iron b. seawater c. salt d. paper

b. seawater (iron = element, salt = compound, paper = organic compound)

17. Each vertical column of the periodic table includes elements with chemical characteristics that are, in general, a. identical b. similar c. different d. sometimes similar and sometimes different

b. similar

29. Relative to the number of electrons in the atoms that join to form a molecule, the number of electrons in the molecule is a. smaller b. the same c. larger d. any of the above, depending on the molecule

b. the same

In order to correctly represent a chemical reaction, a chemical equation must be _____________. That is the same number of atoms exist for a particular element on both sides of the equation.

balanced

What is the term used to describe a chemical equation that contains the same number and type of each atom on each side of the equation?

balanced

A ________ chemical equation is characterized by having the same _________ and type of atoms on both sides of the chemical equation.

balanced; number

Which of the following elements are classified correctly? (Select all that apply.) a. Potassium is an inert gas b. Chlorine is an alkali metal c. Francium is an alkali metal d. Neon is an inert gas

c & d

Which of the following options correctly describe the arrangement of the periodic table? (Select all that apply.) a. Elements in the modern periodic table are arranged in order of increasing atomic mass. b. Elements in the same period have similar chemical properties. c. The horizontal rows of the periodic table are called periods. d. Elements in the same groups have similar chemical properties. e. The groups are numbered 1 to 7.

c, d

Which of the following statements correctly describe the physical properties of metals, nonmetals, and metalloids? (Select all that apply.) a. Nonmetals are good conductors of electricity. b. Metalloids are nonmetals but have physical properties identical to metals. c. Metals tend to be solid at room temperature. d. Metals can be shaped by bending or hammering.

c, d

Which of the following ion combinations will result in an ionic compound that has a balanced number of positive and negative charges? (Select all that apply.) a. Mg2+ and Cl- b. K+ and O2- c. 2 Li+ and S2- d. Ba2+ and 2 Cl- e. Na+ and Br-

c, d, e

34. The number of atoms represented in the formula Ca3(PO4)2 is: a. 8 b. 12 c. 13 d. 16

c. 13

35. The number of hydrogen atoms in a molecule of C3H5(OH)3 is: a. 2 b. 6 c. 8 d. 18

c. 8

32. Sodium chloride crystals consist of a. NaCl molecules b. Na and Cl atoms c. Na+ and Cl- ions d. Na- and Cl+ ions

c. Na+ and Cl- ions

9. Iodine is an example of: a. an inert gas b. an alkali metal c. a halogen d. a compound

c. a halogen

2. Elements can be distinguished unambiguously by their: a. hardnesses b. colors c. atomic numbers d. electrical properties

c. atomic numbers

The most active of the following nonmetals is a. helium b. carbon c. chlorine d. oxygen

c. chlorine

21. In each period of the periodic table, metallic activity a. increases to the right b. remains constant c. decreases to the right d. varies with no regular pattern

c. decreases to the right

24. An inert gas atom a. has one electron in its outer shell b. has two electrons in its outer shell c. has a filled outer shell d. lacks one electron of having a filled outer shell

c. has a filled outer shell (group 18 has 8 in outer shell which is the max)

4. At room temperature and atmospheric pressure, most elements are: a. gases b. liquids c. metallic solids d. nonmetallic solids

c. metallic solids

The most active of the following metals is: a. copper b. lead c. potassium d. gold

c. potassium

6. Which of the following substances is a compound? a. iron b. seawater c. salt d. paper

c. salt

15. Of the following nonmetals, the one not a halogen is: a. fluorine b. bromine c. sulfur d. iodine

c. sulfur

Covalent compounds that contain ______ are called organic compounds.

carbon

The insoluble solid resulting from a chemical reaction in solution is called a _____.

chemical precipitate

When chlorine (Cl2) gas is mixed with hydrogen (H2) gas in the presence of UV light, hydrogen chloride (HCl) gas is produced. This is an example of a ______ reaction where there is ______ in the chemical composition of the substance.

chemical; a change

Inert gases are chemically passive because they have __________ subshells. (Use only one word per blank.)

closed

A + B -----> AB The accompanying image shows the generalized form of a ______ reaction.

combination

When two or more reactants form a single product, it is called a(n) _________ reaction.

combination

Sugar is an example of a(n) ______, whereas carbon is an example of a(n) ______.

compound; element Sugar is a compound as it contains the elements O, H, and C held together by chemical bonds. Carbon is found in the periodic table and is therefore an element.

30. In a covalent molecule, a. at least one metal atom is always present. b. one or more electrons are transferred from one atom to another c. adjacent atoms share one or more electrons d. adjacent atoms share one or more pairs of electrons

d. adjacent atoms share one or more pairs of electrons

The least active of the following metals is: a. copper b. lead c. potassium d. gold

d. gold

23. A halogen atom a. has one electron in its outer shell b. has two electrons in its outer shell c. has a filled outer shell d. lacks one electron of having a filled outer shell

d. lacks one electron of having a filled outer shell (halogen atoms have 7 and want 1 more)

11. Of the following metals, they most active chemically is: a. gold b. aluminum c. iron d. sodium

d. sodium

18. The periodic table of elements does not a. permit us to make accurate guesses of the properties of undiscovered elements b. reveal regularities in the occurrence of elements with similar properties c. include the inert gases d. tell us the arrangement of the atoms in a molecule

d. tell us the arrangement of the atoms in a molecule

Each horizontal row of the periodic table includes elements with chemical characteristics that are, in general,

different

Some elements form ions with ________ charges depending on the chemical circumstance. In order to identify the ion of such an element, a ________ numeral is used to specify the charge.

different; roman

AB + CD --> AD + CB

double displacement

Atomic electrons with the same quantum number n occupy the same ______.

electron shell

Each electron shell in an atom contains

electrons with the same principal quantum number n

A substance that cannot be broken down nor changed into simpler substances by chemical means is called a(n)

element

_______ cannot be broken down into new substances by chemical means.

elements

The law of definite proportions states that in a given chemical compound, the component ______ are present in ______ proportions by mass.

elements; the same

A chemical ________ uses symbols to concisely express the results of a chemical change.

equation

True or false: All compounds consist of molecules.

false There are compounds that do not consist of individual molecular units but instead consist of ions.

What makes the inert gases chemically inactive?

full valence shell of electrons

Molecules are the ultimate particles of a ________ compound.

gaseous

A vertical column in the periodic table is called a _________.

group

Vertical columns of the elements on the periodic table are _______.

groups

An atom whose outer electron shell lacks one electron of being filled is

halogen

A family of elements known for its brilliant colors and extreme odors is the ______.

halogens

A family of elements whose atoms react by picking up electrons is the

halogens

Carbon

has properties intermediate between those of metals and nonmetals (unique in its ability to form strongly bonded chains, sealed off by hydrogen atoms)

Elements with similar properties (other than atomic mass) ___________________________________.

have similar electron configurations

The relative activity of elements can be determined by either measuring the amount of ________ given off in similar chemical reactions or by analyzing the ease with which similar compounds are ________ into their component elements.

heat; separated

A ________ has a variable composition whose parts can be separated by physical means.

heterogeneous mixture

A ______ mixture has the same composition throughout, whereas a ______ mixture does not have a uniform composition.

homogeneous; heterogeneous

What is the most important factor in determining the chemical behavior of an atom?

how the electrons are arranged (atomic #)

The group of elements in the periodic table that are not very chemically reactive are called the ______. These elements are not very reactive because they have a(n) ______ shell.

inert gases; closed

Ionic compounds consist of molecules, atoms, or ions?

ions

The atomic mass of an element is the average atomic _______ of its ______ according to their proportions in nature.

mass; isotopes

Each element in a given compound consists of the same proportion by _________ of the compound. This observation is summarized by the law of definite __________

mass; proportions

______ atoms tend to lose electrons when forming compounds, whereas ______ atoms tend to gain or share electrons when combining chemically with other elements.

metal; nonmetal

The largest number of elements on the periodic table are classified as ___________.

metals

A(n) _________ consists of an independent structure composed of two or more atoms chemically bonded together; examples include oxygen, water, and ammonia.

molecule

The term "______" is not typically used to describe an ionic solid because an ionic solid is not observable as a particle.

molecule

Ionic bonds, which form ionic solids, usually do not result in the formation of _________.

molecules

Ionic compounds in the solid state

never consist of molecules

Is hydrogen an alkali metal?

no. non-metal

What other name are the inert gases called?

noble gases

The elements are arranged in the periodic table in order of increasing atomic ___________. The vertical columns of the table are called __________ or families and the horizontal rows are called _____________ .

number; groups; periods

Covalent compounds that contain carbon are called ________ compounds.

organic

Elements combine to form ionic compounds by gaining or losing ______ electrons. The number of electrons lost must ______ the number of electrons gained in order to form a neutral compound.

outer; equal

A horizontal row in the periodic table is called a

period

The ______ law states that the physical and chemical properties of the elements recur at certain regular intervals when listed in order of increasing atomic ______.

periodic; number

A _________ is an insoluble solid that results from a chemical reaction. (Use only one word per blank.)

precipitate

The insoluble solid that results from a chemical reaction is called a(n) ______.

precipitate

The starting material in a chemical reaction (featured on the left-hand side of the formula) is called a _____, whereas a substance formed in a chemical reaction (featured on the right-hand side of the formula) is called a _____.

reactant; product

The halogens are known as _____ formers

salt

A covalent bond is typically formed between two nonmetals. This bond involves the _____ of one or more electron pairs between the two atoms.

sharing

In a __________ __________ reaction, another element replaces one of the original elements in a compound.

single displacement

Chemically active elements produce very ______ compounds. That is, they are difficult to break apart.

stable

The atomic mass of an element is (hint: you must distinguish between the terms atomic mass and mass number)

the average atomic mass of its isotopes according to their proportions in nature

The statement that elements in a given compound are always combined in the same proportions by mass is known as:

the law of definite proportions

The periodic law states ______.

the physical and chemical properties of elements appear at regular intervals when listed in order of their atomic numbers

As a period is crossed on the periodic table, the elements are dissimilar because the number of ______ varies.

valence electrons