APChem - Chapter 2 Vocabulary

Law of conservation of mass

The total mass of materials present after a chemical reaction is the same as the total mass present before the reaction

Law of multiple proportions

If two elements A and B combine to form more than one compound, the masses of B that can combine with a given mass of A are in the ratio of small whole numbers

subatomic particles

particles such as protons, neutrons, and electrons that are smaller than an atom

Cathode rays

streams of electrons that are when a high voltage is applied to electrodes in an evacuated tube; how electrons were discovered

Electrons

positively charged subatomic particles found in the nucleus of the atom (charge of -1)

alpha (⍺), beta (β), and gamma (𝛾)

Three types of radiation

nucleus

the center of an atom

protons

positively charged subatomic particles found in the nucleus of the atom (charge of +1)

neutrons

subatomic particles with no charge found in the nucleus of the atom

Atomic number

the number of protons in the nucleus of an atom of an element

Gravitational, electromagnetic, strong nuclear, weak nuclear

4 basic forces known in nature

Gravitational forces

attractive forces that act between all objects in proportion to their masses

Electromagnetic forces

attractive or repulsive forces that act between either electrically charged or magnetic objects

​​strong nuclear force

force that holds protons and neutrons together in the atomic nucleus

Weak nuclear force

the force that allows protons to turn into neutrons and vice versa through beta decay; even shorter ranged than the strong force

Mass number

the number of protons plus neutrons in the atom

Isotopes

atoms that have the same number of protons but a different number of neutrons

Atomic mass unit (amu)

one twelfth of the mass of a carbon 12 atom

Atomic weight

the average mass of the atoms of an element in amu; it is numerically equal to the mass in grams of one mole of the element

Periods

horizontal rows

Groups

vertical columns

Metallic (metals) elements

elements that are usually solids at room temperature, exhibit high electrical and heat conductivity, and appear lustrous—shiny

Nonmetallic (nonmetal) elements

elements that some are gaseous, solid, or liquid at room temperature; differ from metals in appearance and in other physical/chemical properties

Metalloids

elements tha have properties that fall between those of metals and nonmetals

Alkali metals

elements in group 1A

Alkaline earth metals

elements in group 2A

Halogens

nonmetals in group 7A

Noble gases (inert gases)

elements in group 8A

Transition metals

elements in group B

Inner transition metals

elements tha appear belwoq the main body of the periodic table

representative elements

elements in groups 1A-7A

chemical formula

a notation that uses chemical symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in a substance

Diatomic molecule

a molecule composed of only two atoms

Molecular compounds

a compound consisting of molecules

Molecular formulas

a chemical formula that indicates the actual number of atoms of each element in one molecule of a substance (ex: C₁₀H₂₂)

Empirical formula

a chemical formula that shows the kinds of atoms and their relative numbers in a substance in the smallest possible whole-number ratios (ex: C₅H₁₁)

structural formula

a formula that shows not only the number and kinds of atoms in the molecule but also the arrangement (connections) of the atoms

Perspective drawings

a model that uses wedges and dashed lines to depict bonds that are not in the the plant of the paper (gives a sense of the three-dimensional shape of a molecule)

Ball-and-stick model

model that depict atoms as spheres and bonds as sticks

Space-filling model

model that shows relative sizes of the atoms

Ion

electrically charged atom or group of atoms (polyatomic ion); ions can be positively or negatively charged, depending on whether electrons are lost (pos) or gained (neg) by the atoms

Cation

an ion with a positive charge

Anion

an ion with a negative charge

Ionic compound

a compound composed of cations and anions

Ionic Bonds

the electrostatic forces that hold ions together in ionic compounds (bonding causes one ion to give away valence electrons to the other)

Covalent Bonds

atoms that are held together by sharing electrons

Molecule

a neutral group of atoms joined together by covalent bonds

Chemical nomenclature

the rules used in naming substances

organic compounds

contain carbon and hydrogen, often in combination with oxygen, nitrogen, or other elements (associated with plants and animals)

inorganic compounds

compounds that are made up of two or more elements other than carbon (associated with nonliving portion of the world)

organic chemistry

the study of carbon-containing compounds, typically containing carbon-carbon bonds

Hydrocarbons

compounds composed of only carbon and hydrogen

Alkanes

compounds of carbon and hydrogen containing only carbon-carbon single bonds (simplest class of hydrocarbons) (alkanes' names end with '-ane')

Isomers

compounds whose molecules have the same overall composition but different structures