Elements of life- basics

Question 1

Define the term isotope:

Answer 1

An isotope is an atom of the same element with the same number of proton but a different number of neutrons- and so different masses.

Question 2

Define the term isotopic mass:

Answer 2

mass of an isotope compared with 1/12 of the mass of a carbon-12.

Question 3

Define the term relative atomic mass (Ar)

Answer 3

The weighted mean mass of one atom of an element compared with 1/12 of a carbon-12.

Question 4

What is the Avogadro’s constant?

Answer 4

The number of particles in 1 mole of a substance-
6.02x10<23

Question 5

How do you calculate the number of moles?

Answer 5

Mass/Mr

Question 6

What is the mass of one mole of oxygen atoms?

Answer 6

16g

Question 7

How many molecules are there in 27g of water?

Answer 7

9x10<23

Question 8

What mass of water is formed when 1.6g of methane burns?

CH4 +2O2= CO2+ 2H20

Answer 8

3.6G OF WATER

Question 9

Define the empirical formula

Answer 9

The simplest formula ratio of atoms of each element in a compound.

Question 10

Define molecular formula

Answer 10

Gives the number of each element in a molecule. Use the empirical formula to find this.