2.1 Periodicity Flashcards Preview

6.02 A Level Inorganic KW > 2.1 Periodicity > Flashcards

Flashcards in 2.1 Periodicity Deck (32)
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What are electron shells really called?

Energy levels


What is the formula to work out the maximum number of electrons in an energy level?



What are the energy sub levels?



Are electrons divided equally between sub levels?



Why don’t we know where electrons are at all times?

They exhibit wave particle duality


What is an orbital?

A volume of space that can hold a maximum of 2 electrons


How many orbitals and maximum electrons does the sub level S have? Which groups?

1 orbital
2 electrons

Group 1 and 2


How many orbitals and maximum electrons does the sub level P have? Which groups?

3 orbitals
6 electrons

Groups 3-0


How many orbitals and maximum electrons does the sub level D have? Which groups?

5 orbitals
10 electrons

Transition metals


How does the electron configuration progress?

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p


What happens the more energy levels there are?

The further away from the nucleus the more energy they have


How can we shorten electron configurations?

Using the noble gases in square brackets

These indicate a full energy levels


What are the two abnormalities in electron configuration?

Chromium (Cr)
Copper (Cu)


What is the correct configuration of Chromium? Why?

[Ar] 4s1 3d5

Chromiums outer shell is half full so it loses an electron out of the s group and gains one in the d group


What is the correct configuration of Copper? Why?

[Ar] 4s1 3d10

Coppers outer shell is full so it loses an electron out of the s group and gains one in the d group


What does each sub level contain?

Electron orbitals which are regions of space in which are electrons are likely to be found


How is the electron configuration of d block ions different?

When d block elements form ions they lose s group electrons rather than d group


How can we represent electrons within sub levels?

Using spin diagrams


What properties do electrons have to do with their positions?

They have a property called spin

It tells us how they occupy orbitals


What are the two rules with spin diagrams?

2 electrons in the same orbital cannot have the same spin state
(Up then down)

Electrons always go into unoccupied orbitals first
(Up, up, up then down, down, down)
(Remember: look for a free seat on the bus)


What is first ionisation energy?

The energy required to remove one mole of electrons from one mole of atoms in the gaseous state

Or energy to remove the outer electron


What must elements be in ionisation energy?

A Gas


How do we remove an electron? What is ionisation energy measured in?

Heat energy is supplied to overcome the attraction of the electrons to the nucleus


How do you write the equations for ionisation energy?

X - any element

X(g) —> X(g)+ + e-
X(g)+ —> X(g)2+ + e-
X(g)2+ —> X(g)3+ + e-

Endothermic reactions


What happens to ionisation energy within individual elements? Why?

It increases

By making the ion positively charged it is harder to remove the next electron as the ion want to hold on to the remaining electrons

It requires more energy to remove the next one


What is changing across a period?

More protons are added therefore the outermost electron has a stronger electrostatic force of attraction to the nucleus


What is significant about electrons added across a period?

They are added within the same principle energy level therefore aren’t further from the nucleus

They are actually closer as atomic radius decreases


Why for individual elements does the ionisation energy vastly increase between 3s1 and 2p6?

The sub level is closer to the nucleus so more energy is required to remove the electron due to a stronger attraction


What is the general pattern of first ionisation energy across period 2 or 3? Anomalies?

It generally increases across a period

Between 3s2 and 3p1
Then 3p3 and 3p4

They are slight decreases


What is the general trend of first ionisation down a group? Why?

It decreases

Less energy is required as the increase in energy levels means the electrostatic force of attraction is weaker to the nucleus


Why is there a decrease in ionisation energy between Mg and Al across period 3?

Mg - 3s2
Al - 3p1

Aluminium’s outer most electron is slightly further away from the nucleus which shows it requires less energy

Despite having more protons


Why is there a decrease in ionisation energy between P and S across period 3?

P - 3p3
S - 3p4

Sulphur’s outer electron is paired with an electron in an orbital therefore a slight repulsion occurs

It has a lower ionisation energy as it is slightly easier to remove