unit 1 - ap chem

mole

mole

unit of measurement for amount of substance / contains 6.022×10²³ atoms

molar mass

the mass of one mole of a substance

avogadro’s number

6.022×10²³ / the number of particles in one mole of a substance

mass spectroscopy / mass spec

used to calculate average atomic mass by identifying isotopes and relative abundances in nature

isotopes

variations of an element that has different NEUTRONS

ions

charged atom/molecule

anion

negatively charged due to the gaining of electrons

cation

positively charged due to the loss of electrons

percent composition / percent comp

the percent an element makes up in a compound

empirical formula

lowest whole number ratio / simplified formula

molecular formula

actual number of atoms in the compound

elemental analysis

finding the relative mass of one or more elements in a mixture

coulomb’s law

electrons closer to the nucleus have stronger attraction / less shells = more attraction

aufbau principle

electrons fill lower energy levels first

photoelectron spectroscopy / PES

experimental technique to determine the relative energies of electrons

less

valence electrons have _________ attraction to the nucleus

atomic radius

the size of an atom / largest atoms at the bottom left of the periodic table

ionization energy

the energy required to remove an electron / easiest to remove are in the top right of the periodic table

electronegativity

the ability of an atom to attract shared electrons in a molecule / larger atomic radius = weaker attraction between nucleus and electrons, smaller atomic radius = stronger attraction between nucleus and electrons / fluorine (top right) has the highest

electron affinity

the energy change when an atom gains an electron to form a negatively charged ion / top right is the highest / nonmetals = easier to gain electrons, metals = easier to lose electrons