C1.2 - Atomic Structure

Question 1

What does the number of protons, neutrons, electrons and mass number tell us?

Answer 1

Number of protons = atomic number

Number of neutrons = mass number - atomic number

Number of electrons = the number of protons ( ONLY IN ATOMS )

Mass number - Number of protons + number of neutrons

Question 2

What is the 12 and the 6?

Answer 2

12 = mass number ( always the largest )

6 = Atomic number

Question 3

What are isotopes ?

Answer 3

Isotopes of an element are the atoms with the same number of protons and electrons ( same atomic number ) but a different number of neutrons ( different mass number )

Question 4

What are ions?

Answer 4

They are charged particles

Question 5

What happens when an atom loses or gains electrons?

Answer 5

• Atoms that lose electrons form positive ions ( cations ) e.g. Na+
• Atoms that gain electrons from negative ions ( anions ) e.g. Cl-

Question 6

When are ions formed ?

Answer 6

When an atom or group of atoms gains or loses one or more electron

Question 7

What did the initial atom model look like? draw it

Answer 7

Question 8

What did the plum-pudding model look like? Draw it

Answer 8

Question 9

What did Earnest Rutherford’s model look like? Draw it

Answer 9

Question 10

What did Niels Bohr’s model look like? Draw it

Answer 10

Question 11

Describe the plum-pudding model?

Answer 11

The model described the atom as a cloud of positive charge which contained smaller negatively charged particles called electrons

Question 12

Describe Earnest Rutherford’s model?

Answer 12

A small positively charged nucleus is found at the centre of the atom, it is surrounded by a cloud of negative electrons. Most of the atom is empty space.

Question 13

What is the timeline for developing the atomic model timeline?

Answer 13

John Dalton ( 1803 ) —> J.J.Thomson ( 1897 ) —> Earnest Rutherford ( 1909) —> Niels Bohr ( 1913 )

Question 14

What did John Dalton suggest?

Answer 14

• That all matter Is made from solid atoms
• All atoms of an element are identical
• Different elements contain different types of atoms

Question 15

What did J.J.Thomson discover and propose ?

Answer 15

• Discovered the electron by experimenting with cathode rays
• Proposed the ‘plum-pudding’ model of the atom to show:
  . Atoms contain electrons
  . Atoms have no overall charge

Question 16

What did Earnest Rutherford do?

Answer 16

He tested the plum-pudding model by firing positively charged alpha particles at gold foil :
- Most particles went straight through the foil but many changed direction
- Some alpha particles bounced back
Therefore, evidence led him to propose that an atom has a positively charged nucleus and that most of the atom was empty space

Question 17

What did Niels Bohr do?

Answer 17

• Used mathematical models to show that electrons occupy fixed shells ( energy levels ) around the nucleus

Question 18

What is an atom ?

Answer 18

The smallest part of an element which still contains its chemical properties

Question 19

What is a molecule ?

Answer 19

Two or more non-metal atoms chemically joined together by covalent bonds

Question 20

What is a bond length?

Answer 20

The distance between the centres of two atoms that are chemically joined together.