Chapter 4 - Atoms and Elements

What are the three parts of Dalton's Atomic Theory?

1) Each element is composed of tiny indestructible particle called atoms. 2) All atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements. 3) Atoms combine in simple, whole-number ratios to form compounds.

What are the three basic parts of the nuclear theory of an atom?

1) Most of the atom's mass and all of it positive charge are contained in a small core called the nucleus. 2) Most of the volume of the atom is empty space through which the tiny, negatively charged electrons are dispersed. 3) There are as many negatively charged electrons outside the nucleus as there are positively charged particles (protons) inside the nucleus so that the atom is electrically neutral. Rutherford created this model.

What is a cation?

A cation is a positively charged ion.

What is a chemical symbol?

A chemical symbol is a one or two letter abbreviation for an element. Chemical symbols are listed directly below the atomic number in the periodic table. Most chemical symbols are based on the English name of an element.

What is a family or group of elements?

A group of elements that have similar outer electron configurations and therefore similar properties. Families occur in vertical columns in the periodic table.

What is a mass number (A)?

A mass number is the sum of the number of neutrons and protons in an atom.

What is a neutron's charge?

A neutron has no charge.

What is a neutron?

A neutron is a nuclear particle with no electrical charge and nearly the same mass as a proton.

What is a nucleus?

A nucleus is the small core containing most of the atom's mass and all of its positive charge. The nucleus is made up of protons and neutrons. The dense nucleus makes up more than 99.9% of the mass of the atom, but occupies only a small fraction of its volume.

What are protons?

A proton is a positively charged nuclear particle. A proton's mass is approx. 1 amu.

What is a proton's charge?

A proton's charge is 1+.

Which elements are alkali metals? a) barium b) sodium c) gold d) tin e) rubidium

Alkali metals b) sodium - Na e) rubidium - Rb

What are alkali metals?

Alkali metals are the group 1A elements which are highly reactive metals.

What are alkaline earth metals?

Alkaline earth metals the group 2A elements, which are fairly reactive metals.

Which elements are alkaline earth metals? a) sodium b) aluminum c) calcium d) barium e) lithium

Alkaline earth metals: c) calcium - Ca d) barium - Ba

Do all atoms have the same number of protons and neutrons?

All atoms of a given element have the same number of protons, but they do not necessarily have the same number of neutrons.

What is all matter made of?

All matter is made of atoms. The atom is the fundamental building block of everything you hear, feel see and experience. Atoms are the building blocks of matter.

What is an anion?

An anion is a negatively charged ion.

What is an atom?

An atom is the smallest identifiable unit of an element.

What is the atomic mass unit (amu)?

An atomic mass unit (amu) is the unit commonly used to express the masses of protons, neutrons, and nuclei. 1 amu = 1.66 X 10^-24 g.

What is an atomic number?

An atomic number is the number of protons in the nucleus of an atom.

What is an electron?

An electron is a negatively charged particle that occupies most of the atom's volume but contributes almost none of its mass. Electrons are distributed through a much larger region, but don't have much mass. JJ Thomson discovered the electron.

What is an electron's charge?

An electron's charge is 1-.

What is an element?

An element is a substance that cannot be broken down into simpler substances. There are about 91 different elements in nature, and consequently about 91 different kinds of atoms. In addition, scientists have made over 20 synthetic elements.

What are ions?

An ion is an atom (or group of atoms) that has gained or lost one or more electrons so that it has an electrical charge. Ions behave very differently than the atoms from which they are formed.

What is an isotope?

An isotope is an atom with the same number of protons but a different number of neutrons. Some elements have one naturally occurring isotope while other elements have two or more.

What is atomic mass?

Atomic mass is a weighted average of the masses of each naturally occurring isotope of an element; atomic mass is the average mass of the atoms of each element.

What are atoms composed of?

Atoms are composed of protons, neutrons and electrons. The number of protons in the nucleus identify the particular element.

Based on their position in the periodic table, what ions do barium and iodine tend to form?

Barium is in group 2A and tends to form a cation with a 2+ charge. Iodine is in group 7A and tends to form an anion with a 1- charge.

Determine the number of protons and electrons in the Ca^2+ ion.

Ca - Calcium has 20 Protons 2+ charge = 20 Protons - 18 electrons Ca^2+ = 20 Protons and 18 Electrons

What are the atomic number (Z) , mass number (A), and symbols of the carbon isotope that has 7 neutrons.

Carbon Atomic Number = 6 Mass Number = 6 + 7 = 13 amu C-13

What is a charge?

Charge is a fundamental property of protons and electrons. Charged particles experience forces such that like charges repel and unlike charges attract.

What are the atomic number, mass number and symbols for the chlorine isotope with 18 neutrons.

Chlorine Atomic Number = 17 Mass Number = 17 + 18 = 35 amu Cl-35

How many protons and neutrons are in the chromium isotope 52 over 24 Cr or Cr-52.

Cr-52 = 24 Protons and 28 Neutrons

Determine the charge of each ion. a) a magnesium ion with 10 electrons b) a sulfur ion with 18 electrons c) an iron ion with 23 electrons

Determine the charge of each ion. a) a magnesium ion with 10 electrons Mg = Protons 12 - 10 electrons = 2+ charge b) a sulfur ion with 18 electrons S = Protons 16 - 18 electrons = 2- charge c) an iron ion with 23 electrons Fe = Protons 26 - 23 Electrons = 3+ charge

Determine the charge of each ion. a) a nickel ion with 26 electrons b) a bromine ion with 36 electrons c) a phosphorus ion with 18 electrons

Determine the charge of each ion. a) a nickel ion with 26 electrons Ni = 28 Protons - 26 Electrons = 2+ charge b) a bromine ion with 36 electrons Br = 35 Protons - 36 Electrons = 1- charge c) a phosphorus ion with 18 electrons P = 15 Protons - 18 Electrons = 3- charge

Determine the charge of each ion. a) oxygen ion with 10 electrons b) aluminum ion with 10 electrons c) titanium ion with 18 electrons d) iodine ion with 54 electrons

Determine the charge of each ion. a) oxygen ion with 10 electrons O = 8 Protons - 10 Electrons = 2- charge b) aluminum ion with 10 electrons Al = 13 Protons - 10 Electrons = 3+ charge c) titanium ion with 18 electrons Ti = 22 Protons - 18 Electrons = 4+ charge d) iodine ion with 54 electrons I = 53 Protons - 54 Electrons = 1- charge

Gallium has two naturally occurring isotopes Ga-69 with a mass of 68.9256 amu and a natural abundance of 60.11%, and Ga-71 with a mass of 70.9247 amu and a natural abundance of 39.89%. Calculate the atomic mass of gallium.

Fraction Ga-69 = 60.11/100 = 0.6011 Fraction Ga-71 = 39.89/100 = 0.3989 Atomic Mass = (0.6011 X 68.9256 amu) + (0.3989 X 70.9247 amu) = 41.4312 amu + 28.2919 amu = 69.7231 amu or 69.72 amu

Magnesium has three naturally occurring isotopes with masses of 23.99, 24.99 and 25.98 amu and naturally abundances of 78.99%, 10.00%, and 11.01%. Calculate the atomic mass of magnesium

Fraction Mg-24 = 78.99/100 = .7899 Fraction Mg-25 = 10.00/100 = .1000 Fraction Mg-26 = 11.01/100 = .1101 Atomic Mass = (23.99 X .7899) + (.1 X 24.99) + (.1101 X 25.98) =44 18.9497 + 2.499 + 2.860398 = 24.309 amu or 24.31 amu

What are halogens?

Halogens are the Group 7A elements which are very reactive nonmetals.

What is the equation of an ion charge?

Ion charge = Number of Protons - Number of Electrons

A fictitious element is composed of isotopes A and B with masses of 61.9887 and 64.9846 amu, respectively. The atomic mass of the element is 64.52. What can you conclude about the natural abundance of the two isotopes? a) The natural abundance of isotope A must be greater than the natural abundance of isotope B. b) The natural abundance of isotope B must be greater than the natural abundance of isotope A. c) The natural abundance of both isotopes must be about equal. d) Nothing can be concluded about the natural abundances of the two isotopes from the given information.

Isotope A = 61.9887 amu Isotope B = 64.9846 amu Atomic Mass = 64.52 b) The natural abundance of isotope B must be greater than the natural abundance of isotope A.

How many protons and neutrons are in the potassium isotope 39 over 19 K or K-39.

K-39 = 19 Protons and 20 Neutrons

What are main-group elements?

Main-group elements are groups 1A - 8A on the periodic table. These groups have properties that tend to be predictable based on their position in the periodic table.

What type of ions does the main-group elements form?

Main-group elements tend to form ions that have the same number of valence electrons as the nearest noble gas.

What is the mass number (A) equation?

Mass Number (A) = Number of Protons + Number of Neutrons

If an atom with a mass number of 27 has 14 neutrons, it is an isotope of which element? a) silicon b) aluminum c) cobalt d) niobium

Mass Number = 27 Atomic Number = 13 b) aluminum

What are metalloids?

Metalloids are those elements that fall along the boundary between metals and nonmetals in the periodic table; their properties are intermediate between those of metals and those of nonmetals. Metalloids are also called semiconductors because of their intermediate electrical conductivity which can be changed or controlled.

Which elements are metalloids?

Metalloids: B - Boron Si - Silicon Ge - Germanium As - Arsenic Sb - Antimony Te - Tellurium Po - Polonium At - Astatine

What are metals?

Metals are elements that tend to lose electrons in chemical reactions. They are found at the left side and in the center of the periodic table. Metals are good conductors of heat and electricity. Metals can be pounded into flat sheets (malleability). Metals can be drawn into wires (ductility). Metals are often shiny. Metals tend to lose electrons when the undergo chemical reactions.

What is a noble gas?

Noble gases are the Group 8A elements which are chemically nonreactive.

What are nonmetals?

Nonmetals are elements that tend to gain electrons in chemical reactions. They are found in the upper right side of the periodic table. Some nonmetals are solids at room temperature and others are gases. Nonmetals as a whole are poor conductors of heat and electricity. Nonmetals tend to gain electrons when they undergo chemical reactions.

What is percent natural abundance?

Percent natural abundance the percentage amount of each isotope of an element in a naturally occurring sample of th element. Each element has its own unique percent natural abundance of isotopes.

Based on their position in the periodic table, what ions to potassium and selenium tend to form?

Potassium is in group 1A and it tends to form a cation with a 1+ charge. Selenium is in group 6A and it tends to form an anion with a 2- charge.

Determine the number of protons and electrons in the S^2- ion.

S - Sulfur has 16 protons 2-charge = 16 Protons - 18 electrons S^2- = 16 Protons and 18 Electrons

What is the mass of a neutron?

The mass of a neutron is 1.67493 X 10^-27 kg or 1.0087 amu.

What is the mass of a proton?

The mass of a proton is 1.67262 X 10^-27 kg or 1.0073 amu.

What is the mass of an electron?

The mass of an electron is 0.00091 X 10^-27 kg or approx. 0.00055 amu.

What is the nature of electrical charge?

The nature of electrical charge is ... a) Electrical charge is a fundamental property of protons and electrons. b) Positive and negative electrical charges attract each other. c) Positive-positive and negative-negative charges repel each other. d) Positive and negative charges cancel each other so that a proton and an electron, when paired, are charge neutral.

What is the periodic law?

The periodic law is a law that states that when the elements are arranged in order of increasing relative mass, certain sets of properties recur periodically.

What is the periodic table?

The periodic table is an arrangement of the elements in which atomic number increases from left to right and elements with similar properties fall in columns called families or groups.

What are transition elements (metals)?

Transition elements or metals are the elements int he middle of the periodic table whose properties tend to be less predictable based simply on their position in the periodic table. Transition metals lose electrons in their chemical reactions but do not necessarily acquire noble gas configurations.

What are valence electrons?

Valence electrons are the outermost electrons in an atom.

Determine the number of protons and neutrons in each isotope. a) 23 over 11 Na b) 266 over 88 Ra c) 208 over 82 Pb d) 14 over 7 N

a) 23 over 11 Na Protons = 11; Neutrons = 12 b) 266 over 88 Ra Protons = 88; Neutrons = 178 c) 208 over 82 Pb Protons = 82; Neutrons = 126 d) 14 over 7 N Protons = 7; Neutrons = 7

How many protons are in the nucleus of an atom of each element? a) Ar b) Sn c) Xe d) O e) Tl

a) Ar - 18 b) Sn - 50 c) Xe - 54 d) O - 8 e) Tl -81

Classify each element as a metal, nonmetal or metalloid. a) Ba b) I c) O d) Te

a) Ba - Metal b) I - Nonmetal c) O - Nonmetal d) Te - Metalloid

Find the atomic number (Z) for each element. a) Fr b) Kr c) Pa d) Ge e) Al

a) Fr - 87 b) Kr - 36 c) Pa - 91 d) Ge - 32 e) Al - 13

To which group or family or elements does each element belong? a) Li b) B c) I d) Ar

a) Li - 1A - Alkali Metal b) B - 3A c) I - 7A - Halogen d) Ar - 8A - Noble Gas

To which group or family of elements does each element belong? a) Mg b) N c) K d) Br

a) Mg - 2A - Alkaline earth metal b) N - 5A c) K - 1 A - Alkali metal d) Br -7A - halogen

Find the name and atomic number for each element. a) Na b) Ni c) P d) Ta

a) Na - Sodium - 11 b) Ni - Nickel - 28 c) P - Phosphorus - 15 d) Ta - Tantalum - 73

Determine the number of protons and electrons in each ion. a) Na+ b) Ba^2+ c) O^2- d) Co^3+

a) Na+ - 11 Protons and 10 Electrons Na - Sodium - 11 Protons 1+ charge = 11 Protons - 10 Electrons b) Ba^2+ - 56 Protons and 54 Electrons Ba - Barium - 56 Protons 2+ charge = 56 Protons - 54 Electrons c) O^2- = 8 Protons and 10 Electrons O - Oxygen - 8 Protons 2- charge = 8 Protons - 10 Electrons d) Co^3+ = 27 Protons and 24 Electrons Co - Cobalt - 27 Protons 3+ charge = 27 Protons - 24 Electrons

Which pair of ions has the same total number of electrons? a) Na+ and Mg^2+ b) F- and Cl- c) O- and O^2- d) Ga^3+ and Fe^3+

a) Na+ and Mg^2+ Na+ - 11 Protons and 10 Electrons Mg^2+ - 12 Protons and 10 Electrons Both of these have 10 electrons.

Predict the ion formed by each element. a) Rb b) K c) Al d) O

a) Rb - Rubidium is in group 1A and it tends to form a cation with a 1+ charge. b) K - Potassium is in group 1A and it tends to form a cation with a 1+ charge. c) Al - Aluminum is in group 3A and it tends to form a cation with a 3+ charge d) O - Oxygen is in group 6A and it tends to from an anion with 2- charge.

Classify each element as a metal, nonmetal or metalloid. a) S b) Cl c) Ti d) Sb

a) S - Nonmetal b) Cl - Nonmetal c) Ti - Metal d) Sb - Metalloid

Classify each element as a metal, nonmetal or metalloid. a) Sr b) Mg c) F d) N e) As

a) Sr - Metal b) Mg - Metal c) F - Nonmetal d) N - Nonmetal e) As - Metalloid

List the symbol and atomic number of each element. a) carbon b) nitrogen c) sodium d) potassium e) copper

a) carbon - C - 6 b) nitrogen - N - 7 c) sodium Na - 11 d) potassium - K - 19 e) copper - Cu - 29

List the atomic symbol and atomic number for each element. a) silicon b) potassium c) gold d) antimony

a) silicon - 14 - Si b) potassium - 19 - K c) gold - 79 - Au d) antimony - 51 - Sb

Determine the atomic number and mass number for each isotope. a) the hydrogen isotope with 2 neutrons b) the chromium isotope with 28 neutrons c) the calcium isotope with 22 neutrons d) the tantalum isotope with 109 neutrons

a) the hydrogen isotope with 2 neutrons Atomic Number (Z) = 1; Mass (A) = 3 amu b) the chromium isotope with 28 neutrons Atomic Number (Z) = 24; Mass (A) = 52 amu c) the calcium isotope with 22 neutrons Atomic Number (Z) = 20; Mass (A) = 42 amu d) the tantalum isotope with 109 neutrons Atomic Number (Z) = 73; Mass (A) = 182 amu

Which statement is NEVER true? a) An element can be both a transition element and a metal. b) An element can be both a transition element and a metalloid. c) An element can be both a metalloid and a halogen. d) An element can be both a main-group element and a halogen.

b) An element can be both a transition element and a metalloid. All of the metalloids are main-group elements.

An atom composed of which of these particles would have a mass of approx. 12 amu and be charge-neutral? a) 6 protons and 6 electrons b) 3 protons, 3 neutrons and 6 electrons c) 6 protons, 6 neutrons and 6 electrons d) 12 neutrons and 12 electrons

c) 6 protons, 6 neutrons and 6 electrons The mass in amu is approx. equal to the number of protons plus the number of neutrons. In order to be charge-neutral, the number of protons must equal the number of electrons.

Which element is a main-group metal? a) O b) Ag c) P d) Pb

d) Pb - Lead is a main-group metal