3.1 electron theory

Question 1

What are the main subatomic particles and their electric charges?

Answer 1

Protons are positively charged, neutrons are neutral, and electrons are negatively charged.

Question 2

What is the structure of an atom?

Answer 2

An atom consists of protons and neutrons in the nucleus, with electrons orbiting around it.

Question 3

What is the charge of a single electron?

Answer 3

The charge of a single electron is negative.

Question 4

What is the charge of a single proton?

Answer 4

The charge of a single proton is positive.

Question 5

What is the elementary charge?

Answer 5

The elementary charge is the magnitude of the charge of a proton or electron, denoted by the symbol e.

Question 6

What makes an atom electrically neutral?

Answer 6

An atom is electrically neutral if it has an equal number of protons and electrons.

Question 7

What is a negatively charged atom called?

Answer 7

A negatively charged atom is called a negative ion.

Question 8

What is a positively charged atom called?

Answer 8

A positively charged atom is called a positive ion.

Question 9

What defines a molecule?

Answer 9

A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.

Question 10

What is an example of a molecule of an element?

Answer 10

The molecule of the element oxygen is made up of two oxygen atoms (O2).

Question 11

What is an example of a compound?

Answer 11

Sodium chloride (NaCl) is an example of an ionic compound made up of sodium and chlorine.

Question 12

How are positive ions formed?

Answer 12

Positive ions are formed when an atom loses an electron.

Question 13

How are negative ions formed?

Answer 13

Negative ions are formed when an atom gains an electron.

Question 14

What are the two main types of compounds covered in this module?

Answer 14

The two main types of compounds are molecules held together by covalent bonds and ionic compounds held together by ionic bonds.

Question 16

What is the molecular structure of conductors?

Answer 16

In a conductor, such as metals, atoms are closely packed in a crystal lattice, allowing electrons in the outer shells to move freely. This high electron mobility makes metals good conductors of electricity and heat.

Question 17

What are examples of good conductors?

Answer 17

Examples of strongly conductive metals include copper, aluminium, and silver.

Question 18

What defines a semiconductor?

Answer 18

A semiconductor is a material whose conductivity is between that of a good conductor and a good insulator. Its conductivity can be affected by temperature, doping, or light.

Question 19

How does temperature affect semiconductors?

Answer 19

Semiconductors are better conductors at higher temperatures, unlike metals which are poorer conductors at higher temperatures.

Question 20

What is the typical number of free electrons in semiconductors?

Answer 20

Semiconductors have a small number of free electrons compared to metals, typically one free electron per million atoms at room temperature.

Question 21

What is the atomic structure of semiconductors?

Answer 21

Semiconductors generally contain atoms with four electrons in their outer shell (valence orbit).

Question 22

What are examples of semiconductors?

Answer 22

Examples of semiconductors include silicon and germanium.

Question 23

What is the structure of insulators?

Answer 23

In insulators, electrons are tightly connected to atoms or molecules, preventing them from breaking away and resulting in no free electrons for conduction.

Question 24

What defines good insulators?

Answer 24

Good insulators contain atoms having more than four electrons in their outer shell (valence orbit).

Question 25

What are examples of good insulators?

Answer 25

Examples of good insulators include mica and porcelain.