Chemistry

Branches of Chemistry

Organic (carbon), Inorganic (no carbon), Physical (matter/energy), Analytical (identification), Biochemistry (living things), Theoretical (math and tech

Types of Research

Basic (want or need to increase knowledge), Applied (solving practical problems), Technological development (use of existing knowledge to make life easier and more convenient)

Law of Conservation of Mass/Energy

Energy can be absorbed/released but never created or destroyed- only converted from one form to another

Homogeneous solution

same, pure substance (chocolate milk)

Heterogeneous solution

different, mixture (pizza, juice with pulp)

scientific notation

positive exponent (move to right) negative exponent (move to left)

significant figures

Non zeros, #’s between, and zeros after decimal before 1-9 are significant, placeholders are not

Addition and Subtraction sig fig problems

round to least number of places after the decimal

multiplication and division sig fig problems

final answer matches the lowest sig fig count among equation numbers

Density, Mass, Volume

d=m/v, m=dxv, v=m/d

John Dalton

atomic model/ theory (each compound is composed of atoms that are identical)

Law of definite proportions

Elements are combined in a compound and their ratio will always be a whole definite number

Mass number

protons+neutrons

Neutrons

mass number-atomic number

isotope

same number of protons but different number of neutrons

Stanislao Cannizzaro

accurately measured atomic masses of atoms and other properties

Dimitri Mendeleev

noticed trend of elements and their increasing atomic masses/ created 1st periodic table

Henry Mosley and Ernest Rutherford

modern periodic table based on increasing atomic numbers of elements

John Strutt and William Ramsey

discovered Aron and how it wasn’t reactive

Ionic Compounds

metal and nonmetal (add ide to the end of second element)

cation

positively charged ion (usually metal)

anion

negatively charged ion (usually nonmetal)

Metals tend to lose electrons and form positive ions.

Nonmetals tend to gain electrons and form negative ions.

What happens when ions with the same charge get near each other?

repel/bounce off each other

What happens when ions with different charge types get near each other?

attract/compel each other

Covalent Compounds

mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca

Octet Rule

all elements want their ourtermost energy level to be full

chemical bond

attractive force that holds atoms or ions together

ionic bonding

force that attracts electrons from one atom to another, transforms a neutral atom into an ion

covalent bonding

formed when atoms share one or more pairs of electrons

molecule

group of atoms held together by chemical forces

chemical formula

combination of chemical symbols/numbers to represent a subject

lewis dot structure

formula in which electrons are represented by dots

resonance

bonding in molecules or ions that can’t be correctly represented by a single lewis structure

ionic compound

composed of ions bonded together by electrostatic attraction

formula unit

collection of atoms corresponding to an ionic compound’s formula so the molar mass is the same as mass of 1mol of formula units

lattice energy

energy associated with constructing a crystal lattice relative to the energy of all constituent atoms separated by infinite distances

polyatomic ion

made of two or more atoms

metallic bonding

bond formed by the attraction between positively charged metal ions and the electrons around them

malleability

ability of a substance to be hammered or beaten into a sheet

ductility

ability of a substance to be hammered thin or drawn out into a wire

VSEPR theory

predicts some molecular shapes based on the idea that pairs of valence electrons surrounding an atom repel each other

Hybridization

mixing of two or more atomic orbitals of the same atom to produce new orbitals

dipole

molecule that contains positively and negatively charged regions

hydrogen bonding

intermolecular force occurring when a hydrogen atom bonded to a highly electronegative atom is attracted to two unshared electrons of another molecule

Law of Conservation of Mass

mass cannot be created nor destroyed

Law of Multiple Proportions

two elements combine to form two or more compounds

Nuclear forces

interaction that binds protons and neutrons together in a nucleus

Nuclide

atom identified by the number of protons and neutrons

Atomic Mass Unit

unit of mass that describes the mass of an atom or molecule

Average Atomic Mass

weighted average of all naturally occurring isotopes of an element

Mole

SI base unit used to measure amount of substance with number of particles same as number of atoms

Avogadro’s Number

6.02×10²³ number of atoms or molecules in 1mol

molar mass

mass in grams of 1mol of a substance