Atomic Structure

Question 1

What charge is a nucleus, electron and an atom?

Answer 1

Nucleus - positively charged
Electron - negatively charged
Atom - neutral

Question 2

What is the atomic number?

Answer 2

Number of protons in an atom

Question 3

What is the mass number?

Answer 3

The total number of protons and neutrons in an atom

Question 4

Explain why a substance is an element?

Answer 4

Because it cannot be broken down chemically and contains only one type of atom

Question 5

Describe the main stages in the development of atomic structure illustrating the provisional nature of evidence

Answer 5

• Dalton’s atomic theory
• J.J. Thompson (discovery of the electron)
• Rutherford (nuclear atom)
• Bohr (electron orbits)

Question 6

What is a nucleus made from?

Answer 6

Protons and neutrons

Question 7

Recall the relative charge and relative mass of an electron, a proton and a neutron

Answer 7

• electron charge -1 and mass 0.005 (0)
• proton charge +1 and mass 1
• neutron charge 0 and mass 1

Question 8

Describe isotopes

Answer 8

Varieties of an element that have the same atomic number but different mass numbers

Question 9

Describe the arrangement of elements in the Periodic Table

Answer 9

• Columns are called groups, rows are called periods

- elements in the same group have the same number if electrons in the highest occupied energy level (outer shell)

Question 10

Explain the identity of an element can be deduced from its electronic structure

Answer 10

1. Find the element in the periodic table. Work out which period it is in, and draw that number of circles around the nucleus
2. Work out which group the element is in and draw that number of electrons in the outer circle
3. Fill the other circles with electrons
4. Count your electrons and check that they equal the atomic number

Question 11

Describe Dalton’s atomic theory snd how the work or J.J.Thompson, Rutherford and Bohr contributed to the development of the theory of atomic structure

Answer 11

• the theory changed as new evidence was found

- science explanations are provisional but more convincing when predictions are later confirmed

Question 12

Explain why an atom is neutral in terms of its sub-atomic particles

Answer 12

Atoms contain 3 sub-atomic particles, the number of electrons in an atom is always the same as the number of protons, so atoms are electrically neutral overall.

Question 13

What is the radius and mass of an atom?

Answer 13

Radius -10⁻¹⁰m

Mass - 10⁻²³g

Question 14

Identify isotopes from data about the number of electrons, protons and neutrons in particles

Answer 14

Isotopes have the same atomic number but a different mass number

Question 15

Deduce the electronic stricture of the first 20 elements in the periodic table

Answer 15

2.8.8.2

Question 16

Explain the significance of the work of Dalton, J.J. Thompson, Rutherford and Bohr in the development of the theory of atomic structure

Answer 16

• unexpected results (e.g, Geiger and Marsden’s experiment) led to the theory of a nuclear atom

Question 17

What does an atom have?

Answer 17

A nucleus surrounded by electrons