chemistry exam terms

electron group geometry 2 bonds/0lone pairs

linear = 180 degrees

electron group geometry 3 bonds/0 lone pairs

trigonal planar = 120 degrees

electron group geometry 4 bonds/0 lone pairs

tetrahedral = 109.5

molecular geometry 3 bonds, 0 lone pars

trigonal planar

molecular geometry 2 bonds, 1 lone pair

bent

molecular geometry 4 bonds, 0 lone pairs

tetrahedral

molecular geometry 3 bonds, 1 lone pair

trigonal pyrimidal

molecular geometry 2 bonds, 2 lone pairs

bent

when elements are molecules they are:

covalent bonds (non-metal, non-metal)

octet rule

states atoms tend to have 8 valence e⁻ (e.g., c, n, o. f)

duet rule

applies to light elements (h, he, li) with stable w 2 valence in their first shell

How is bond strength determined?

Shorter bond length = higher bond strength; single>double>triple

polar covalent bond

bond that results from unequal sharing of electrons

non-polar covalent bond

bond that results between identical atoms with electronegativity balance of 0 w = sharing of electrons

cation

positviely chared ion when atom loses one or more electrons (Na⁺, Ca²⁺)

anion

negatively charged ion formed when anion gains 2+ electrons (Cl⁻, SO₄²⁻)

ion

atom/molecule w an electrical charge → caution/ion from gain + loss of e-

atom

smallest unit of an element w chemical properties of that element → nucleus + electrons

chemical bond

force that holds 2 atoms together, lower energy states are more stable than higher ones, noble gases are the most stable/lowest energy

ionic bond

electrostatic force that holds oppositely charged particles together in an ionic compound; transfer of electrons between atoms

single bond

1 pair of electrons shared between 2 atoms

concentration

measure of how much solute is dissolved in a specific amount of solvent/solution → expressed through molarity

diatomic molecules

I₂, H₂, B₂, F₂, O₂, Cl₂, N₂

solution

homogenous mixture w solids, liquids, or gases

aqueous solution

1+ substances dissolved in water

solute

substance dissoved in water

solvent

water, most in solution + what solvents are dissolved in

percipitate

dookie solid at the bottom of the mixture

spectator ions

ions that don’t change in the reaction

chemical change

process involving one or more substances changing into a new substance

chemical reaction

chemical change (e.g. temp change, energy released as heat/light, absorption of heat, color change, odor, gas bubbles, solid formation)

synthesis

2 or more substances react to form a single product: A + B → AB

combustion

oxygen combines w a substance and releases energy in the form of heat and light; A + O₂ → AO, CH + O₂ → CO₂ + H₂

decomposition

a single compound breaks down into 2 or more elements/compounds; AB → A + B

single replacement

atoms of 1 element replace atoms of another element in a compound: A + BC → AC + B

double replacement

ions exchange between 2 compounds: AB + CD -> AD + CB

what is stoichiometry based off of?

law of conversation of mass thats why total mass of reactants must = total mass of products

molecular compounds

compounds that u do the greek letters w → covalently bonded

where are halogens on the periodic table?

group 17 (reactivity decreases as u go down)