Atomic stucture

Question 1

What force holds protons and neutrons together?

Why does this need to be strong

Answer 1

Strong nuclear forces

To overcome repulsion between protons

Question 2

Which isotope is more reactive?

7Li or 9Li

Answer 2

They have the same reactivity because they have the same number of electrons

Question 3

Give a practical use of isotopes

Answer 3

Carbon dating

Question 4

Why is the proton number the same as the electron number in an atom?

Answer 4

An atom has a neutral charge, therefore the equal and opposite charges of p+ and e- must cancel each other out

Question 5

How do you find the Ar/Mr of a substance?

Answer 5

Average mass of 1 atom or molecule / 1/12 mass of 1 atom of 12C

Question 6

What are the 4 stages of mass spectrometry?

Answer 6

🔹Ionisation
🔹Acceleration
🔹Ion drift
🔹Detection

Question 7

Why does mass spectrometry occur in a vacuum

Answer 7

So that ions do not collide/react with molecules from the air

Question 8

Describe ionisation in mass spectrometry

Answer 8

Atoms enter in the form of a gas and are bombarded with e-

This causes every atom to lose 1 e- and become a positive ion

Question 9

Describe acceleration in mass spectrometry

Answer 9

The positive ions are attracted towards a negatively charged plate and accelerate towards it

Question 10

In mass spectrometry, what is the relationship between mass to charge ration and speed?

Answer 10

Ions with a lower mass and higher charge travel at a higher speed

Question 11

Define ionisation energy

Answer 11

The energy required to remove 1 e- from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous ions

Question 12

What 3 factors affect ionisation energy?

Answer 12

1) charge of nucleus
2) distance from nucleus
3) shielding

Question 13

What has a higher IE?
11Na or 13Al

Explain why

Answer 13

Aluminium
🔹more protons, stronger nuclear charge

🔹smaller atom so outer e- is closer to nucleus

🔹requires more energy to remove e- so IE is higher

Question 14

Which element has the highest IE?
15P or 16S

Explain why?

Answer 14

Phosphorus

There is e- pair repulsion in sulphur (3p4) so outer e- is easier to remove

Question 15

Which element has the highest IE?
12Mg(G2) or 13Al(G3)

Explain why

Answer 15

Magnesium

Aluminium has a new sub shell (from S to P) so e- is further away from nucleus and is easier to remove

Question 16

How does the nuclear charge effect ionisation energy?

Answer 16

More protons = greater force of attraction between nucleus and e- so more energy is required to remove e-

Higher nuclear charge = higher IE

Question 17

How does the distance of the e- from the nucleus effect ionisation energy?

Answer 17

Electrons closer to the nucleus will feel a greater force of attraction and will require more energy to remove

Smaller distance = higher IE

Question 18

How does shielding effect ionisation energy?

Answer 18

More shielding = lower IE

Because outer e- feel a lesser force of attraction as they are further away

Question 19

What are nucleons?

Answer 19

Protons and neutrons.

Question 20

Between which groups does IE not fit the trend?

Answer 20

2&3

5&6

Question 21

What is the unit of ionisation energy?

Answer 21

KJ/mol

Question 22

Does the atomic radius increase or decrease along the period?

Answer 22

Decreases

Question 23

Why does atomic radius decrease along each period?

Answer 23

• More protons
• More positive charge
• Stronger FoA between positive nucleus and negative e-

Same shell so same shielding