Periodicy

Question 1

How are elements arranged in the periodic table?

Answer 1

By increasing atomic number

Question 2

What do elements in the same period have in common?

Answer 2

Highest energy electron in the same shell

Question 3

What do elements in the same group have in common?

Answer 3

Same number of electrons in the highest energy shell

Question 4

How and why did Mendeleev arrange the elements?

Answer 4

By atomic weight

Nothing was known about sub atomic particles

Question 5

Define periodicy

Answer 5

Trends in properties of elements in the periodic table

Question 6

Define ionisation energy

Answer 6

The energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous 1+ ions

Question 7

What factors affect ionisation energy?

Answer 7

Atomic radius

Nuclear charge

Shielding

Question 8

How does shielding affect ionisation energy?

Answer 8

Inner shell electrons repel outer shell electrons making them easier to remove

Question 9

How does atomic radius affect ionisation energy?

Answer 9

Larger atomic radius means electrons are further away from nucleus

Less attraction

Easier to remove

Question 10

How does nuclear charge affect ionisation energy?

Answer 10

Larger means larger attraction

Electrostatic force of attraction stronger means more energy needed to break

Question 11

How do successive ionisation energies provide evidence for atomic structure?

Answer 11

Large increase suggests electrons are closer to nucleus.

Evidence for shells

Number of electrons removed before increase indicates electrons in outer shell

Question 12

Does ionisation energy increase or decrease down a group?

Why?

Answer 12

Decreases

Larger atomic radius (more shells)

More shielding (more shells)

Larger nuclear charge (outweighed by other factors )

Question 13

Does ionisation energy increase or decrease across a period?

Why?

Answer 13

Increases

Nuclear charge increases

Atomic radius decreases

Shielding is similar so no effect

Question 14

Why is there an unexpected decrease between ionisation energies between group 2+3 and 5+6?

Answer 14

2+3 = P subshell begins to fill (further from nucleus means easier to remove)

5+6= electrons begin to pair so feel repulsion (easier to remove)

Question 15

What are semi metal?

What is another name for them?

Answer 15

Elements either side of the metal non-metal divide

Metalloid

Question 16

What is the structure of metals and giant covalent molecules know as?

Answer 16

Giant lattice

Question 17

Why are metals not soluble?

Answer 17

They react instead

Partial charges not strong enough to break strong metallic bonds

Question 18

What is the shape of diamond and silicone?

Answer 18

Tetrahedral

Question 19

What is the difference between graphene and graphite ?

Answer 19

Graphite = layers of graphene

Question 20

What is the structure of graphite ?

Answer 20

Giant planar structure

Question 21

Are giant covalent structures soluble?

Why?

Answer 21

Not soluble

Partial charges can’t break strong covalent bonds

Question 22

Why is there a general increase in melting points across the metals in the same period?

Answer 22

Higher charge on ion

More delocalised electrons

More stronger forces to overcome

Question 23

Where and why do the melting points of elements peak across period 3?

Answer 23

At silicone

Silicone is a giant covalent structure

Phosphorus is a simple molecule

Covalent VS weak London forces

Question 24

Order in decreasing strength giant covalent , simple molecules and ionic (metallic) bonding .

Answer 24

Covalent ionic simple

Question 25

Why does silicone have a higher melting point than phosphorus ?

Answer 25

Silicone = S8

Phosphorus = P4

Larger molecule = more electrons = stronger induced dipoles = stronger London forces