Week 13 Flashcards

1
Q

Core electrons

A

Inner electrons
Held tightly to the nucleus
Do not take part in bonding

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2
Q

Valence electrons

A

Electrons in outer shell
Held less tightly due to shielding from core electrons
Participate in bonding and responsible for a lot of chemistry

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3
Q

Shielding

A

Core electrons repel valence electrons
They act like a shield to prevent the outer electrons feeling the full charge of the nucleus

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4
Q

Z eff number

A

Z is nuclear charge also know as atomic number or the number of protons
Effective nuclear charge = Z eff
- attraction felt by the valence electrons
Z eff = Z - S
S = number of core electrons

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5
Q

Z eff and atomic radius

A

As Z eff increases electrons are held more tightly into the nucleus
Smaller atomic radii
Z eff decreases to bottom left
Atoms get smaller across a period
Atoms get larger down a group

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6
Q

Ionisation energy

A

Ion - atom or compound with an overall charge
Ionisation energy - kJ/mol
When Z eff increases attraction is stronger - ionisation energy increases across a period
When electrons are close to the nucleus attraction is stronger - ionisation energy decreases down a group

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7
Q

Electron affinity

A

amount of energy released when an electron attaches to a neutral atom or molecule in its gaseous state to form an anion

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8
Q

Photoemission spectroscopy

A

Measures energy of ejected electrons
Light only penetrates into the material a few nm so surface analysis technique
Non destructive
Very sensitive
Trace analysis
High resolution

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9
Q

XPS vs UPS

A

X ray photoelectric spectroscopy probes core electrons

Ultraviolet photo electron spectroscopy probes valence electrons and chemical bonding

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