Chapter 2 Key Terms

Front 1

Law of conservation of mass

Back 1

In a chemical reaction mass is neither created or deystroyed

Front 2

Law of definite proportions

Back 2

All samples of a given compound regardless of where they come from will be composed will have the same proportions

Front 3

Law of multiple proportions

Back 3

When two elements form two different compounds, the mass of one element that combines with 1 gram of the other element can be expressed as a ratio of small whole numbers ie. the ratios of the 2 compounds will have a ratio of whole numbers

Front 4

Atomic theory

Back 4

1) each element is composed of small indestructible particles called atoms.
2)All atoms of the given element have the same mass and properties.
3) Atoms combine in whole number ratios to form compounds
4)Atoms cannot change in a chemical reaction, only the way the are bound to other atoms

Front 5

Cathode rays

Back 5

a beam of particles traveling from the negative charged electrode to the positive, in a cathode tube

Front 6

Cathode ray tube

Back 6

A glass tube, with much of the air pumped out, with electrical cathodes, of a particular element on either side

Front 7

Electrical charge

Back 7

A fundamental property of some particles that compose atoms and result in attractive and repulsive forces between those particals

Front 8

Electron

Back 8

a negatively charged, low mass particle present with all atoms

Front 9

Radioactivity

Back 9

the emission of small energetic particles from the core of certain unstable atoms

Front 10

Nuclear theory

Back 10

1) most of the mass in an atom is located in the nucleus 2) most of the atoms volume is empty space 3) atoms contain the same number of electrons and protons

Front 11

Nucleus

Back 11

the center of an atom, where the protons and neutrons are located

Front 12

Proton

Back 12

a positively charged particle located in the nucleus of an atom

Front 13

Neutron

Back 13

a particle with no charge located in the nucleus of an atom having a mass almost equal to a proton

Front 14

Atomic Mass unit (amu)

Back 14

the unit to express the mass of a single proton or neutron. equal to 1/12th of a carbon atom containing 6 protons and 6 neutrons

Front 15

Atomic Number (Z)

Back 15

The number of protons in an atoms nucleus

Front 16

Chemical symbol

Back 16

a 1 or 2 letter abbreviation for each element

Front 17

Isotope

Back 17

an atom with the same number of protons but a different number of neutrons

Front 18

Natural abundance

Back 18

the percentages of each isotope that make up a "natural" sample of an element

Front 19

Mass Number (A)

Back 19

the sum on protons and neutrons in an atom

Front 20

Ion

Back 20

atoms that lose or gain an electron becoming a charged partical

Front 21

Cation

Back 21

a positively charged ion by losing an electron

Front 22

Anion

Back 22

a negatively charged ion by gaining an electron

Front 23

Periodic law

Back 23

when elements are arranged in order of increasing mass a certain set of properties recur periodically

Front 24

Metal

Back 24

are on the lower left side and middle of the periodic table. common properties are good conductors of heat and electricity are malleable often shiny, usually lose electrons in chemical change

Front 25

Nonmetal

Back 25

are on the upper right of the periodic table, common properties are poor conductors of heat and electricity, and tend to gain an electron in a chemical reactions

Front 26

Metalloid

Back 26

are in a zig-zag line between Boron and Astatine, have a mixture of properties

Front 27

Semiconductor

Back 27

elements where the conductivity of heat and electricity are temperature dependent

Front 28

Main group elements

Back 28

the group of elements whose properties tend to be largely predictable, located on the left and right of the periodic table, labeled with the letter A

Front 29

Transition elements/metals

Back 29

the group of elements whose properties are less predictable, located in the middle of the periodic table labeled with the letter B

Front 30

Family (group)

Back 30

each column in the main group of the periodic table

Front 31

Noble gases

Back 31

8A the least reactive group on the periodic table

Front 32

Alkali metals

Back 32

1A highly reactive metals

Front 33

Alkaline earth metals

Back 33

2A reactive metals, slightly less than 1A

Front 34

Halogens

Back 34

7A are very reactive nonmetals

Front 35

Atomic Mass

Back 35

the average mass of an element made up of all its isotopes

Front 36

Mass spectrometry

Back 36

a device to measure the make up of an atom or compounds percentage of isotopes

Front 37

Mole (mol)

Back 37

the unit of measure of particles, or the number of atoms

Front 38

Avogadro's number

Back 38

1 mol = 6.022 x 10²³ particles

Front 39

Molar mass

Back 39

the grams per mole is equal to the elements atomic mass in atomic mass units