The Changing Nucleus

Question 1

What is ionic bonding?

Answer 1

When atoms give away electrons to another atom.

Atom- gains/loses electrons- becomes positively or negatively charged ion

Question 2

What happens when an atom gives away an electron?

Answer 2

It becomes a “positive ion”- this is because it now has more protons than its electrons orbiting the nucleus

Question 3

Name several features of ionic compounds

Answer 3

• Overall charge of zero
• Include both metals + non-metals
• Has positive ions (cations) and negative ions (anions)
• Has strong ionic bonds
• Has 3 dimensional lattice of positive and negative ions
• Are solid at room temperature
• Has both high melting and boiling points
• Conduct electricity
• Dissolve in water
• Are brittle

Question 4

Name several features of covalent compounds

Answer 4

• Are only non-metals
• Have molecules (group of atoms joined by covalent bonds)
• Molecules have weak bonds
• Are liquid or gas at room temperature (low melting and boiling points)
• Do not conduct electricity
• Not all these substances dissolve in water
• Are soft

Question 5

What is atomic number?

Answer 5

Number of protons the element has in its atom

Question 6

What is mass number?

Answer 6

Sum of the number of protons and neutrons in an atom

Question 7

What is radioactive decay?

Answer 7

When an unstable atomic nucleus loses energy in the form of emitted particles or electromagnetic waves (aka radiation)

*Think-
Unstable atomic nucleus- loses energy (as emitted particles or electromagnetic waves)- forms radiation.

Question 8

What are isotopes?

Answer 8

Atoms of the same element (therefore having the same number of protons) which differ in the number of neutrons in their nucleus

Question 9

What is radioactivity?

Answer 9

The energy or particles from the nucleus of unstable atoms

Question 10

What is covalent bonding?

Answer 10

Simply- sharing of electrons

Question 11

What is the difference between atoms and molecules?

Answer 11

Atoms- single neutral particles
eg. Mg

Molecules- 2 or more atoms bonded together
eg. O2, Co2, NaCl

Question 12

Elements vs compounds

Answer 12

Elements- only one type of atom

Compounds- 2 or more different types of atoms

Question 13

Define the term ‘half-life’

Answer 13

The time taken for a sample of a radioactive substance to decrease its radioactivity by a half

Question 14

What is the nuclear symbol for alpha particles?

Answer 14

4/2 α (has 2 protons and 2 neutrons)

Question 15

What is the nuclear symbol for beta particles?

Answer 15

0/-1 B (mass is so small it can be considered to be zero, charge is -1 which is written as its mass number)

Question 16

What is a nuclear reaction?

Answer 16

One that involves a change in the number of protons and/or neutrons in the nucleus.

• always involves release of radiation
• whenever nuclear reaction occurs, a new element is formed
• The element that is formed depends on the type of radioactive particle that is released

Question 17

What happens when atoms have too many neutrons in its nucleus?

Answer 17

They often release beta particles during radioactive decay.
During beta decay, neutron -changes into a proton and an electron- proton remains in the nucleus- electron (beta particle) is released.

Question 18

What are benefits of nuclear energy?

Answer 18

No Co2 emitted and very useful for medical imaging and cancer treatment

Question 19

What problems are associated with nuclear energy?

Answer 19

Radioactive waste product can remain hazardous for 60,000 years, an accident can be dangerous