Unit 1: Atomic Structure

protons and neutrons

protons and neutrons

subatomic particles in the nucleus

electrons

subatomic particles in the outer shells of the atom

1 amu

mass of protons and neutrons

mass number

protons + neutrons

atomic number

number of protons / nuclear charge

number of neutrons

mass number - atomic number

number of electrons

equals the number of protons

Isotopes

atoms of the same element and same atomic number but different mass numbers

atomic mass

average mass of isotopes by abundance

mass spectrometer

identifies isotopes; each peak represents a different isotope and height = relative abundance

photoelectron spectroscopy

each peak represents a subshell, and the height of the peak represents the number of electrons; peaks further to the left have an increased binding energy and are part of a lower energy level.

binding energy

energy required to remove an electron from the corresponding shell

core electrons

inner electrons

valence electrons

outer electrons

s sublevel

2 e-

p sublevel

6 e-

d sublevel

10 e-

f sublevel

14 e-

aufbau principle

to “build up” electrons are added to the lowest subshell first

Mg electron configuration

Sulfur electron configuration

S^(2-) electron configuration

Gallium electron configuration

Phosphorus electron configuration

Neon electron configuration

Rhodium electron configuration

Coulomb’s Law

Coulombic force = (charge on particle 1 * charge on particle 2) / distance between particles²

charge increases, distance decreases

Coulombic force increases when

Effective Nuclear Charge

approximate nuclear charge felt by the outer electron due to shielding by the core electrons

Electron affinity

energy released when an electron is added to an atom

Cation

positively charged ion (Ca2+)

Anion

negatively charged ion (Cl-)

empirical formula

mole ratio of elements in a compound in simplest form

molecular formula

(molar mass / mass of empirical formula) * empirical formula

% composition

(mass of X / molar mass of compound) * 100

Pb

element?

S2O

How to find empirical formula