Unit 1- Periodic trends

Atomic Theory

• All matter is composed of atoms

• Elements of the same type are composed of similar subatomic molecules

• Chemical reactions are rearrangements of atoms

The ground state is…

The lowest possible energy state

the wavelength is…

the distance between 2 repeating points (minima or maxima; highest or lowest)

Equation of wavelength and frequency of light

(Wavelength)(Frequency) = speed of light

c = λv

• c = speed of light

• v = frequency

• λ = wavelength

What are shells?

Energy levels (1, 2, 3, …)

what are sub-shells?

the more specific energy levels (s,p,d,f)

what are orbitals

areas where electrons are found and can house 2 electrons each

Hunds Rule

electrons will fill empty orbitals first before pairing up and they must have reciprocal spins

only elements that are liquid at room temperature

Bromine and mercury

only elements that are gas a room temp

H, N, O, F, Cl

Periodic number

How many protons an atom has

Weighted atomic mass

average mass depending on isotope abundance

Isotopes

Atoms with same amount of protons but differing amounts of neutrons

C-14 has 6 protons and 8 neutrons, C-12 has 6 protons and 6 neutrons

Ions

Atoms with the same amount of protons but differing electrons

Cations

positive ion (missing electron)

Anion

negative ion (gained electron)

A mole is

6.022 E 23 particles

Molarity (inc. Equation)

concentration in terms of volume

molarity = moles of solute / liters of solution

planck’s equation

E = hv

• E = change in energy (joules)

• h = Planck’s constant (6.626 E -34)

• v = frequency

To move energy levels (shells)

electrons must release or absorb energy

Octet rule

most atoms are stable with 8 electrons in its outer shell

rows

x-axis

groups

y-axis

The s subshell can hold…

2 electrons

The p subshell can hold…

6 electrons

The d subshell can hold…

10 electrons

The f subshell can hold…

14 electrons

Aufbau Principle

electrons will fill up orbitals with the lowest energy level

Effective nuclear charge (Z eff)

The net positive charge that an valence electron feels from a nucleus in a multi-electron atom

Z_{eff}

Z (atomic number) - S ( core electrons)

Coulombs Law

describes the attraction and repulsion between charged particles

Atomic Radii periodic trends

increases down a group

decreases left → right

Ionization energy periodic trends

decreases down a group

increases across a period left → right

Electron Affinity periodic trends

decreases down a group

increases across a period left → right

Electronegativity periodic trends

decreases down a group

increases across a period left → right

Electron Shielding

when valence electrons are repelled by core electrons

Ionization Energy

Energy required to remove an electron

Factors that influence Ionization energy

• Nuclear effective charge

• Electron shielding

• Nuclear charge

• Distance of electron

First and second Ionization energies

each consecutive IE will be larger than the former

a huge jump in Ionization energy means that…

you removed a core electron

Electron affinity

the energy released when an electron is added to a neutral atom

Electronegativity

how much an atom wants an atom