C1 Elements (page 97)

Question 1

What is an Element?

Answer 1

It is a substance made up of Atoms that all have the SAME number of PROTONS in their nucleus.

Question 2

What do Elements consist of?

Answer 2

Elements consist of Atoms with the same Atomc Number

Question 3

How is a type of Atom decided?

Answer 3

Its the number of Protons in the Nucleus that decides what type of Atom it is.

Atoms can have different numbers of Protons, Neutrons and Electrons.

Question 4

What type of Atom has ONE Proton in its Nucleus?

Answer 4

Hydrogen

Question 5

What type of Atom has two Protons in its Nucleus?

Answer 5

Helium

Question 6

If a substance only contains Atoms with the same number of Protons, what is this called?

Answer 6

An Element

(there are about 100 different elements)

Question 7

Do all the Atoms of a partiular element (eg; nitrogen), have the same number of protons?

Answer 7

Yes

And different elements have atoms with different numbers of protons.

Question 8

Atoms of each element are represented by a one or two letter symbol.

What do the following symbols mean on the periodic table?

C =

O =

Mg =

Na =

Fe =

Pb =

Answer 8

C= Carbon
O= Oxygen
Mg= Magnesium
Na = Sodium
Fe = Iron
Pb - Lead

Question 9

What are Isotopes?

Answer 9

They are different forms of the same element, which have the same number of Protons, but a different number of Neutrons

Question 10

Isotopes are the same as Elements, except for extra what?

Answer 10

Neutrons

Question 11

True or False?

Do Isotopes have the same atomic number and the same mass number?

Answer 11

False

Isotopes have the same atomic number but different mass numbers

Question 12

What is Relative Atomic Mass (Ar)? - small r)

Answer 12

Relative Atomic Mass is an average mass, taking into account the different masses and abundances (amounts) of all the isotopes that make up the element

Question 13

Why is Relative Atomic Mass (Ar) used?

Answer 13

It is used because many elements can exist as a number of different isotopes. so relative atomic mass is used instead of mass number when referring to the element as a whole.

Question 14

What is the formula to work out the ‘Relative Atomic Mass’ of an element?

Answer 14

Relative Atomis Mass (Ar) =

sum of (isotope abundance x isotope mass number)
_________________________________________
Sum of abundances of all the isotopes

eg: copper has two stable isotopes. CU-63 has an aundance of 69.2% and Cu-65 has an abundance of 30.8%. calculate the relative atomic mass of copper to 1 decimal place.

Relative atomic mass =

(6.2x63) + (30.08 x 65) 4359.6 = 2002 6361.6
________________________ _______________ __________
69.2 + 30.8 = 100 = 100 = 63.616 = 63.6

Question 15

A substance consists of atoms which all have the same number of protons and electrons but different numbers of neutrons. Explain why this substance is an element?

Answer 15

It is the number of protons in an atom that determines what type of atom it is, so if all the atoms have the same number of protons then the substance is an element.

Question 16

Silicon, SI, has three stable isotopes. Si-28 has an abundance of 92.2%,Si-29 has an abundance of 4.7% and Si-30 has an abundance of 3.1%, calculate silicon’s relative atomic mass to 1 decimal place?

Answer 16

Relative atomic mass =

(92.2 x 28) + (4.7 x 29) + (3.1 x 30)
___________________________________
92.2 + 4.7 + 3.1

= 2581.6 + 136.3 + 83 2810.9
_______________________ _______
100 = 100

= 28.109 = 28.1