midterm #2 full review

dalton’s atomic theory

• all matter consists of atoms; tiny indivisible particles that cannot be created or destroyed

• atoms of one element cannot be converted into atoms of another element

• atoms of an element are identical in mass and other properties but are different from the atoms of any other element

• compounds result from the chemical combination of a specific ration of atoms of different elements

law of conservation of mass

states that matter cannot be created or destroyed

law of constant composition

states that a specific compound is composed of the same elements in the same mass fractions

law of multiple proportions

states if elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole numbers

nucleons

protons and neutrons

atomic number(z)

• the number of protons in the nucleus of an atom

• determines the identity of the atom

• found above the element symbol

• can indicate number of electrons

neutral atom

when the total positive charge is equal to the total negative charge(p+ = e-)

groups

• vertical columns that contain a “family of elements” that are most chemically similar to eachother

• elements have the same valence electron configuration

periods

horizontal rows that display a predictable repeated pattern of chemical properties

alkali metals

name for elements in group 1a(except for H)

alkaline earth metals

name for elements in group 2a

halogens

name for elements in group 7a(17)

nobel gases

name for elements in group 8a(18)

mass number(a)

• not on the periodic table

• the number of protons plus the number of neutrons

isotopes

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

• same atomic number but different mass number

• atoms of the same element

ion

an atom or molecule that has lost or gained one or more electrons

ion charge

determined by the number of protons minus the number of electrons

cation

positively charged ion bc it has lost one or more electrons

anion

negatively charged ion bc it has gained one or more electrons

diatomic elements

elements that exist naturally as a molecule composed of 2 atoms of the same type bonded together

• Hydrogen

• Oxygen

• Nitrogen

• Fluorine

• Chlorine

• Bromine

• Iodine

polyatomic elements

elements with more than 2 atoms bonded

empirical formula

indicates the smallest whole-number ratio between the atoms(or ions) in the compound

molecular formula

indicates the actual number of atoms of each element in a single molecule of the compound

atomic mass

• weighted average mass of atoms of the element

• units in amu

molecular mass

• sum of the atomic masses for each element in the formula

• units in amu

molar mass

• mass of one mole of the substance

• units in grams per mole(g/mol)

• same as the atomic mass for monatomic elements

frequency and wavelength

the two variables that describe the properties of electromagnetic radiation

speed of light

constant that is the product of multiplying frequency and wavelength

quantum theory

• the energy of a small particle is quantized: it occurs in fixed quantities, rather than being continuous

• each fixed quantity of energy or “packet” is called a photon

the bohr model

model representing:

• the orbits around the nucleus that each correspond to a fixed energy level

• electrons can jump between energy levels but cannot exist between them

ground state

the lowest energy orbit(n=1)

excited states

all other energy orbits other than the ground state

absorbs

an electron ______ a photon if it moves from a lower to a higher orbit

emits

an electron ______ a photon when it moves from a higher to a lower orbit

atomic orbital

a 3D standing wave that describes where an electron is most likely to be found and its associated energy

principal quantum number

• describes the energy level and general size of the orbital

• larger # = higher energy and farther from the nucleus

• written as the number in orbital notation

angular quantum number

• describes the shape of the orbital region where the electron is most likely found

• written as the letter in orbital notation

• either s, p, d/f

magnetic quantum number

• describes the orientation of the orbital in 3D space

• each unique orientation is written as a unique subscript

pauli exclusion principle

• states that no two electrons in the same atom can have identical values for all four quantum numbers

• since an orbital can hold a max of two electrons they must be opposite spin(like a shoebox)

electron configuration

the lowest energy subshell assignments for all electrons in an atom

the aufbau principle

a systematic method for determining the energy order of subshells

hund’s rule

specifies that when orbitals of equal energy are available, the lowest energy electron configuration has the max number of unpaired electrons with parallel spins

partial orbital diagram

shows only the highest energy subshells being filled

condensed electron configuration

has the element symbol of the previous noble gas in square brackets

core electrons

electrons an atom has in common with the previous noble gas and any completely filled d or f subshells 

valence electrons

electrons in the highest energy level

ionic bonding

result of transferring electrons from one atom to another

covalent bonding

result of sharing electrons between atoms

isoelectronic

describes the relationship between two ions that have the exact same configuration

polyatomic ion

ions that have covalent bonding between the atoms within the ion but also participate in ionic bonding between other ions

ionic compounds

• contain oppositely charged ions held together by ionic bonding

• attracted to each other through electrostatic forces

• usually formed when a metal combines with a non-metal

• must be electrically charged neutral

molecular compounds

• occur when electrons are shared between two atoms

• exist as discrete, neutral molecules

• usually formed between non-metals