IQ2: Atomic Structure & Atomic Mass

Ion

are atoms or molecules with a net electric charge due to the loss or gain of one or more electron

Isotopes

Are different forms of the same element, with a different number of neutrons and different nucleus masses

Order in which electrons fill orbitals

1. Electrons fill the lowest available energy orbitals that they can. 2. in subshells, electrons first fill orbits singly before they buddy up. They spin upwards first.

S Orbital

1 orbital, 2 electrons, sphere shaped

P Orbital

3 orbitals, 6 electrons, dumbell shape

D Orbital

5 orbitals, 10 electrons, daisy shape

F Orbital

7 orbitals, 14 electrons, complex shape (undefined)

Energy Level Symbol

1 = K, 2 = L, 3 = M, 4 = N, 5 = O

Relative Atomic Mass

Ar = relative isotopic mass x relative abundance) + (relative isotopic mass x relative abundance) / 100

Bohr Model

electrons obit in energy levels and electrons can move between energy levels by emitting or absorbing photons (emit = move down and absorb = move up)

Emission Spectrum - Spectral Evidence of Bohr’s model

Arises when atom of higher levels move to lower levels → Emit photons with energy based on difference in energy levels → Photons of of diff. energy will have diff. colour or wavelength

Absorption Spectrum - Spectral Evidence of Bohr’s model

When white light is shone on an atom, photons absorb to move electrons to higher levels → photons absorbed will have energies that match specific wavelengths → spectrum of light will be missing colours

Flame Test

When atoms are given extra energy (in form of heat), electrons get excited, jump to higher energy levels in atom. Electrons fall back from higher energy level to ground state. as this happens they emit light

Nuclear reaction

a reaction in which change occurs to the nucleus of an atom. as the atomic number increases, there is an increase in ratio of protons to neutrons

Ratio of Protons to Neutrons within Periodic table

Atomic No < 20 → 1:1

Atomic No approx. 50 → 1:1.3

Atomic No approx. 80 or above → 1:1.5

Atomic No > 80 → radioactive + nucleus unstable

Types of Radiation

Alpha → 4, 2 He (positive charge, penetrate stop by sheet of paper)

Beta → e - (negative charge, penetrate stop by sheet of aluminium)

Gamma → (no charge, stopped by 5cm lead or 15cm concrete)