chemistry chapter 4

14

14 scientists were important to the development of the modern periodic table

1-4

1st shell=2 2nd shell=8 3rd shell=18 4th shell= 32

PERIOD

A horizontal row of the periodic table is called a period. periods are not alike in properties but there is a pattern to the properties.

common

Although the alkali metals have very few familiar uses as the elements, their compounds are some of the most important substances we use every day. Table salt, baking soda, and soap are just a few of the compounds made from alkali metals. Compounds that contain alkali metals are (common, rare).

correct

Because of increasing ATOMIC NUMBER an element always has one more electron and proton than the previous element in the table. When an electron is added to an atom, it must go into the correct energy shell

1

How many electrons are in the HIGHEST energy shell (farthest away) of hydrogen, lithium, sodium, and potassium?

18

Only a fixed number of electrons are accommodated in any shell or orbit. A very simple equation tells the maximum number of electrons that can be in a shell. Shell electron capacity = 2n2 First shell (n = 1) holds 2 * 12 = 2 electrons Second shell (n = 2) holds 2 * 22 = 8 electrons How many electrons can the third shell (n = 3) hold?

true

So far, we have seen that everything is made of atoms. Atoms of different elements combine in specific ratios to form chemical compounds. All matter is made up of elements, compounds, or mixtures of elements and/or compounds. (true, false)

alkali metals

The alkali metals are the most reactive of all metals. They are never found uncombined in nature. In pure form, they are stored under oil to keep them from reacting with oxygen or water vapor in the air

2

The elements are classified in several ways. The two most common classification systems are: 1. A system based on electron configuration in which the elements are described as Representative (A-groups) or Transition (B-groups). 2. A system based on physical properties in which the elements are described as Metals or Non-Metals. How many different ways are used to classify the elements?

alkaline earth

The elements in group IIA are the ALKALINE EARTH metals. These elements are harder, denser, and have higher melting points than the alkali metals. These elements are also highly reactive but not as reactive as the alkali metals. Because they are reactive they are never found uncombined in nature. the alkaline earth metals become more reactive as you go down the group. Are the ALKALINE EARTH metals always found combined with other elements in nature? (yes,

halogens

The elements in group VIIA are known as the HALOGENS. The name 'halogen' is a Greek word which means salt producing. All the halogens are very reactive and are never found uncombined in nature. They react with metals to form salts. Are the halogens ever found uncombined in nature? (no)

noble gases

The elements in group VIIIA are known as the NOBLE GASES. All the elements in this group are colorless gases that are extremely unreactive. Because they don't combine with other elements they are referred to as 'noble' or 'inert.'

Names

The elements in the 'A' groups are called the representative elements. Many of these groups have been given names. the A groups have been given special names.

diatomic

The halogens are gases or easily converted to gases because they have low boiling points. In the gas phase the halogens exist as diatomic molecules. Remember a diatomic molecule always contains two atoms. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid.

stair like dark line seperates the metals from non metals

The periodic table easily shows which elements are metals and which are non-metals. Look at the periodic table. There is a stair-like dark line on the right hand side. This line separates the metals from the non-metals. Non-metals are on the right-hand side of this dark line while metals are on the left hand side. Hydrogen, a non-metal, is the one exception to this rule.

111 elements

There are 111 known elements. The majority of the elements are metals. There are 89 metals and 22 non-metals.

third

There are ten elements between calcium and gallium. The third energy shell can hold 10 more electrons after argon. The elements; Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn result when the last 10 electrons fill the third energy shell. The elements between calcium and gallium have electrons in which energy shell. (second, third, fourth)

group

a vertical arrangement of elements in the periodic table

similar

an electron shell in an atom contains electrons of similar energy

no

are non metals a good conductor of electricity. Many of the non-metals like hydrogen, oxygen, and nitrogen are gases at room temperature. Solid non-metals include carbon, sulfur, and phosphorus. Solid non-metals usually have lower densities and melting points than metals.

periodic table

attempts to classify elements led to the

groups

columns in the periodic table are called groups.

quantum mechanics

describes the electron arrangement in terms of their energies

shells

electrons in the modern atomic theory can be grouped into main energy levels called shells. shells have an approximate location of electrons

Group IA

elements are called ALKALI METALS the word alkali means base. bases were first found in the ashes of burned plants. the reaction of an alkali metal with water produces a strong base. alkali is word for base. they are always found in nature combined with other elements

representative

elements are in the A groups of the periodic table they include most of the more common elements

transition

elements are in the b groups of the periodic table they include most of the more common metallic elements

true

elements within a group or column have similar but not identical properties.

supplied

energy must be supplied when an electron goes to a higher orbit

periodic table

important information about each element is given by the

yes

in some cases can electrons be in a higher shell before the lower shell is filled?

atomic number

in the modern periodic table elements are arranged according to increasing atomic number

metal

is an element that has metallic luster is a thermal and electrical conductor and is malleable

non metal

is an element when solid that has a low luster is a thermal and electrical insulator and is usually brittle.

silica

is composed of non-metals

non-metal

is the human body mostly?

similar properties

mandeleev was trying to group elements with similar properties together

noble gases

many different kind of lights use noble gases

true

non metals can be either gases or solids

number

orbits or energy levels in the Bohr atom are identified by a quantum number

energy levels

orbits or energy levels that electrons move

1-7

orbits or energy shells are identified by a number. the shells assigned numbers 1-7 \1= lowest energy 7= highest energy the larger shells have more electrons

electrons

properties of an element are determined by the arrangemenet of it's electrons around the nucleus

overlap

shells greater than 3 have an overlap in their energies

high

the alkaline earths form oxides which have high melting points

energy

the amount of energy determines the most probable location of an electron in the modern atomic model

electrons

the arrangement of electrons in an atom determines it's chemical properties

highest

the chemical properties of an element are determined by the electrons in the highest energy shell

location

the exact location of an electron can't be determined.

salts

the halogens when combined with metals produce

protons

the identity of an element is determined by the number of protons

fourth

the last electron for potassion or calcium will go into what shell. Remember there is an energy overlap for the larger shells (three and greater). Because quantum mechanics says that energies are like climbing stairs, the next lowest energy for the next two electrons, 19 and 20, will be in fourth shell.

n=1

the lowest energy orbit in bohrs model closest to the nucleus.

quantized

the most important characteristic of an electron arrangement is that it's energy is quantized. because an elect4rons energy is quatized it can only have specific values

unreactive

the noble gases are

groups

the periodic table groups the elements according to their chemical and physical properties

valence

these outermost electrons are called valence electrons

true

valence electrons of one atom interact with valence electrons of another atom when they are close together

outermost

when atoms come together only the electrons in the outermost shell interact

same

when building atoms electrons go into the same energy shell until it's full

periodic law

when elements are arranged in the order of increasing atomic number, their chemical and physical properties show repeatable or periodic trends.

repeated

when the elements are arranged according to increasing atomic weight the chemical properties are repeated

yes

will the alkali metals conduct electricity