Atomic Structure

Question 1

What particles are atoms made up of?

Answer 1

1) Protons
2) Neutrons
3) Electrons

Question 2

What is the “mass number” of an element?

What is the “atomic number” of an element?

Answer 2

The amount of protons and neutrons it has

The number of protons it has.

Question 3

What is the “mass” and “charge” of a proton, neutron and electron?

Answer 3

Proton mass = 1. Proton charge = 1.
Neutron mass = 1. Neutron charge = 0
Electron mass = 0, Electron charge = -1

Question 4

Where are protons, neutrons and electrons found in an atom?

Answer 4

• Protons & Neutrons are in the nucleus (in the centre)

- Electrons are in shells around the outside

Question 5

Why do atoms have no electric charge?

Answer 5

They have the same number of protons ( +1 positive charge) and electrons (-1 negative charge)

Question 6

What is an isotope?

Why are their chemical properties the same?

Answer 6

An atom with the same number of protons, but a different number of neutrons.

Because they contain the same number of electrons.

Question 7

What is the “relative atomic mass” of an element and how do you calculate it?

Answer 7

The average mass of atoms of that element taking into account the mass and amount of each isotope it contains.

Question 8

How are electrons arranged on the outside of the nucleus?

Answer 8

In “shells” or “energy levels”. They will occupy the lowest/closest energy level.

The first level holds 2 electrons
The second & thirds level holds 8 electrons
The fourth level holds 2 electrons

Question 9

What are “ions”?

Does a positive ion have more protons or electrons?

Answer 9

Atoms that have an electric charge because they do not have the same amount of protons and electrons.

A positive ion has more protons, as protons are positively charged.

Question 10

What is the charge of an ion with 16 protons and 18 electrons?

Answer 10

-2

Because there are 16 positive protons and 18 negative electrons. 16 - 18 = -2.

Question 11

What is the difference between the “plum-pudding model” and the “nuclear model” which is now accepted today?

Answer 11

The plum-pudding model said that the atom was a ball of positive charge with negative electrons spread about.

However, this was disproven when alpha particles (He2+) where passed through the particle and some of them bounced back (suggesting there is something in the middle that is positively charged)

The nuclear model says there is a positive nucleus (of protons and electrons) with electrons in shells on the outside of this.