Atomic structure
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What is the relative charge and mass of protons?
Protons Relative charge: 1+ Relative mass: 1
What is the relative charge and mass of neutrons?
Neutrons Relative charge: 0 Relative mass: 1
What is the relative charge and mass of electrons?
Electrons Relative charge: 1- Relative mass: 1
What does an atom consist of?
• nucleus containing positively charged protons and neutral charged neutrons • negatively charged electrons orbit nucleus in energy levels/shells
What is the maximum number of electrons that each shel can hold?
1st shell - 2 electrons 2nd shell - 8 electrons 3rd shell - 18 electrons 4th shell - 32 electrons
How many orbitals are there in each sub-shell?
s sub-shell: 1orbital p sub-shell: 3 orbitals d sub-shell: 5 orbitals f sub-shell: 7 orbitals
What is the highest energy electron?
• Electron furthest away from the nucleus ———-> highest energy electron (f) s, p, d, f
What is the electron configuration of Argon?
1s2 2s2 2p6 3s2 3p6
What is the electron configuration of Al2+?
1s2 2s2 2p6 3s1
What is the electron configuration of F-?
1s2 2s2 2p6
What are the 2 exceptions of the d-block atoms? Explain why
Chromium: 1s2 2s2 2p6 3s2 3p6 4s1 3p5 - more stable with a half full d sub-shell Copper: 1s2 2s2 2p6 3s2 3p6 4s1 3d10 - more stable with a full d sub-shell
What are the exceptions of d-block ions? Explain why
Fe2+: 1s2 2s2 2p6 3s2 3p6 3d6 - Electrons lost from 4s sub-shell - 4s – first in – first out Cu2+: 1s2 2s2 2p6 3s2 3p6 3d9 - 4s sub-shell empties first
Does the 3d sub-shell or 4s sub-shell have higher energy?
3d sub-shell
What is an orbital?
A region around the nucleus that can hold up to 2 electrons
Define first ionisation energy
The amount of energy needed to remove one mole of electrons from one mole of atoms in the gaseous state
What is the equation for the 1st ionisation energy of boron?
B (g) —-> B+ (g) + e-
What is the equation for the 3rd ionisation energy of magnesium?
Mg2+ (g) —-> Mg3+ (g) + e-
What is the general trend of atomic radius across period 3? Explain why
• Atomic radius decreases • As nuclear charge increases • Shielding stays the same • So greater attraction between outer electrons and nucleus
What is the general trend in ionisation energies across period 2? Explain why
-General increase - Nuclear charge increases - Atomic radius increases - Shielding stays the same
What 2 elements deviate from the general trend in ionisation energies across period 2? Explain why
Boron: 1s2 2s2 2p1 - outer electron removed from 2p sub-shell - 2p sub-shell is higher in energy - so less energy required to remove outer electron Oxygen: 1s2 2s2 2p4 - outer electron removed from 2p sub-shell from a paired orbital - less energy required to remove outer electron - due to electron pair repulsion
What is the trend in ionisation energies down a group? Explain why
• Decrease in ionisation energies • Increase in atomic radius • Due to increased shielding • Weaker attraction between outer electrons and nucleus
What are the 3 factors that influence ionisation energies? Explain why/how
N D S Nuclear charge: - Increase in nuclear charge - stronger attraction between outer electrons and nucleus - Increases ionisation energies Distance from nucleus/atomic radius: - decrease in atomic radius - stronger attraction between outer electrons and nucleus - increases ionisation energies Shielding - decreased shielding - stronger attraction between outer electrons and nucleus - increases ionisation energies
What is the general trend in ionisation energies across period 3? Explain why
• General increase • Increase in nuclear charge • Decrease in atomic radius • Same shielding • So greater attraction between outer electrons and nucleus
What 2 elements deviate from the general trend of 1st ionisation energies in period 3?
Aluminium and Sulfur