Chemistry-1 EXAM REVIEW

Atomic Mass

(chemistry) the mass (in atomic mass units) of an isotope of an element

phase

(physical chemistry) a distinct state of matter in a system

atom

(physics and chemistry) the smallest component of an element having the chemical properties of the element

Dalton's Atomic Theory

1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements

Atomic Mass Unit (amu)

1/12 the mass of a carbon-12 atom

precipitate

A solid that forms and settles out of a liquid mixture

Transition Metal

An Element in group 3 through 12 of the periodic table

Alkali Metals

Group 1, 1 electron in outer level, very reactive, soft, silver, shiny, low density; Lithium, Sodium, Potassium, Rubidium, Cesium, Francium

Alkali Earth Metals

Group 2, 2 electron in the outer energy level, very reactive but less reactive than alkali metals, silver, higher densities than alkali metals; Beryllium, Magnesium, Calcium, Strontium, Barium, Radium

substance

Matter that has a uniform and definite composition

protons

Positively charged particles

Octet Rule

States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons

Hertz

The SI unit of cycles per second

Electronegativity

The ability of an atom to attract electrons when the atom is in a compound

wavelength

The distance between crests of waves, such as those of the electromagnetic spectrum.

Polar bond

Unequal sharing of electrons

group

Vertical column of elements in the periodic table

Cathode Ray

a beam of electrons emitted by the cathode of an electrical discharge tube

triple covalent bond

a bond formed by sharing three pairs of electrons

Covalent Bond

a bond formed when atoms share one or more pairs of electrons

double covalent bond

a bond that involves two shared pairs of electrons

Physical change

a change from one state (solid or liquid or gas) to another without a change in chemical composition

chemical change

a change that produces matter with a different composition than the original matter

molecular formula

a chemical formula of a molecular compound

product

a chemical substance formed as a result of a chemical reaction

reactant

a chemical substance that is present at the start of a chemical reaction

molecular compound

a compound composed of molecules

solution

a homogeneous mixture of two or more substances

Period

a horizontal row of elements in the periodic table

heterogeneous mixture

a mixture in which the composition is not uniform throughout

homogeneous mixture

a mixture in which the composition is uniform throughout

Diatomic Molecule

a molecule consisting of two atoms

dipole

a molecule that has two poles

Anion

a negatively charged ion

Halogens

a nonmetal in group 7A of the periodic table

chemical symbol

a one or two letter representation of an element

unshared pair

a pair of valence electrons that is not shared between atoms

mixtures

a physical combination of substances that can still be seperated

Cation

a positively charged ion

extensive property

a property that depends on the amount of matter in a sample

intensive property

a property that depends on the type of matter in a sample, not the amount of matter

physical property

a quality or condition of a substance that can be observed or measured without changing the substance's composition

atomic orbital

a region of space in which there is a high probability of finding an electron

liquid

a substance in the fluid state of matter having no fixed shape but a fixed volume

compound

a substance made up of atoms of two or more different elements joined by chemical bonds

Polyatomic Ion

a tightly bound group of atoms that behaves as a unit and has a positive or negative charge

Periodic Table

an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group

Pauli Exclusion Principle

an atomic orbital may describe at most two electrons, each with opposite spin direction

Aufbau Principle

an electron occupies the lowest-energy orbital that can receive it

Inner Transition Metal

an element in the lanthanide or actinide series; the highest occupied s sublevel and nearby f sublevel of its atoms generally contain electrons; also called inner transition element

Metalloid

an element that has some characteristics of metals and some characteristics of nonmetals

element

any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter

Isotopes

atoms of the same element that have a different number of neutrons

spectrum

colored band produced when a beam of light passes through a prism

Metallic bonds

consist of the attraction of the free-floating valence electrons for the positively charged metal ions

Nonpolar covalent bond

covalent bond where electrons are shared equally

Hund's Rule

electrons occupy orbitals of the same energy in a way that makes the number or electrons with the same spin direction as large as possible

Ionic Bonds

electrostatic forces that hold ions together in ionic compounds

Nonmetals

elements that are usually dull in appearance, poor conductors of heat and electricity, gases at room temperature

Representative Elements

groups of elements in the modern periodic table that are designated with an A (1a through 8a) and possess a wide range of chemical and physical properties

Metals

have a shiny or metallic luster, good conductors of heat and electricity

Heisenberg Uncertainty Principle

it is impossible to know exactly both the velocity and the position of a particle at the same time

Photons

light quanta

vapor

matter that exists in the gas state but is generally a liquid or solid at room temperature

Alloys

mixtures composed of two or more elements, at least one of which is a metal

polar molecule

molecule in which opposite ends have opposite electric charges

Electrons

negatively charged particles

solid

of definite shape and volume

Noble gases

one of the elements of group 18 of the periodic table(helium, neon,argon, krypton, xenon, and radon); noble gases are unreactive

Atomic Radius

one-half the distance between the nuclei of two atoms of the same element when the atoms are joined

Electromagnetic radiation

radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge

structural formula

represents the covalent bonds by dashes and shows the arrangement of covalently bonded atoms

Chemical Formula

shows the elements in the compound and the ratio of atoms

chemical property

the ability of a substance to undergo a specific chemical change

quantum

the amount of energy needed to move an electron from one energy level to another

mass

the amount of matter in an object

volume

the amount of space occupied by an object

Nucleus

the center of an atom

Valence Electrons

the electrons that are in the highest energy level of an atom and that are involved in chemical reactions

ionization energy

the energy required to remove one electron from a neutral atom of an element

Energy Levels

the fixed energies an electron can have

Amplitude

the height of a wave's crest

Halide Ions

the ions that are produced when atoms of chlorine and other halogens gain electrons

ground state

the lowest energy state of an atom

Formula Unit

the lowest whole-number ratio of ions in an ionic compound

quantum mechanical model

the modern description of the electrons in atoms

Coordination Number

the number of ions of opposite charge that surround each ion in a crystal

frequency

the number of wave cycles to pass a given point per unit of time

Atomic Number

the order of an element in Mendeleyev's table of the elements

neutrons

the particles of the nucleus that have no charge

atomic emission spectrum

the pattern formed when light passes through a prism or diffraction grating to separate it into the different frequencies of light it contains

chemical reaction

the process by which one or more substances change to produce one or more different substances

distillation

the process of purifying a liquid by boiling it and condensing its vapors

filtration

the process that separates a solid from the liquid in a heterogeneous mixture

gas

the state of matter distinguished from the solid and liquid states by: relatively low density and viscosity

Law of Conversation of Mass

the total mass of the matter is the same before and after a physical or chemical change

Mass Number

the total number of protons and neutrons in the nucleus of an atom

single covalent bond

two atoms held together by sharing a pair of electrons

Molecule

two or more atoms held together by covalent bonds

Periodic Law

when the elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties