Week 1 Language Of Chemistry

Question 1

What are the seven internationally recognised units?

Answer 1

Metre - length
Kilogram - mass
Seconds - time
Kelvin - temperature
Mole - amount of substance in moles
Ampere - electric current
Candela - luminous intensity

Question 2

What is Kelvin?

Answer 2

Degrees centigrade + 273.15

Question 3

What are the two types of numbers in chemistry

Answer 3

Exact - countable

In exact - measured (e.g. By ruler). Limited in accuracy by accuracy of equipment used for measurement

Question 4

What are significant figures and their purpose?

Answer 4

A way of expressing uncertainty
For +/- equations: calculated result has same no. of decimal places as number with least decimal places
For x/ equations: result has same number of significant figures as measurement with least significant figures

Question 5

What is the difference between precision and accuracy

Answer 5

Precision - how close each answer is to each other

Accuracy - how close each answer is to correct answer

Question 6

Difference between empirical and molecular formula

Answer 6

Empirical shows exact number of atoms in molecule

Molecular formula shows ratios

Question 7

How are binary compounds named?

Answer 7

By element farthest to left of periodic table
In same group the lowest appears first
Ionic compounds - cation then anion

Question 8

How are covalent compounds named?

Answer 8

Carbon - hydrogen - everything else in alphabetical order