Chapter 1

Question 1

What are the subatomic particles found in an atom?

Answer 1

protons, neutrons, electrons

Question 2

What does the atomic number tell you?

Answer 2

The number of protons in the atom

Question 3

What is the charge on a proton?

Answer 3

Positive

Question 4

What is the charge on an electron?

Answer 4

Negative

Question 5

How do you find the number of neutrons?

Answer 5

atomic mass - atomic number

Question 6

Which two subatomic particles have a mass?

Answer 6

protons and neutrons

Question 7

How do you find the number of electrons?

Answer 7

It is the same as the number of protons so by looking at the atomic number

Question 8

What is an isotope?

Answer 8

It is an atom with the same number of protons and electrons but different numbers of neutrons

Isotopes of the same element have the same properties

Question 9

What is a mixture?

Answer 9

A mixture consists of two or more elements or compounds not chemically combined together. The chemical properties of each substance in the mixture are unchanged.

Question 10

Where do the electrons sit in an atom?

Answer 10

In shells (orbitals) around the nucleus.

Question 11

How do you find the mass number of an element?

Answer 11

Add the protons and neutrons together

Question 12

How many electrons can the second and third shells hold?

Answer 12

8

Question 13

How many electrons can the first shell hold?

Answer 13

2

Question 14

What is the average size of an atom?

Answer 14

1x10^-10 m

Question 15

What is atomic mass realtive to?

Answer 15

Different atoms have different masses. Atoms have such a small mass it is more convenient to know their masses compared to each other. Carbon is taken as the standard atom and has a relative atomic mass (Ar) of 12.

Atomic mass is defined as being ​one twelth of the atomic mass of a carbon-12 atom.

Question 16

What was Daltons model of the atom?

Answer 16

Solid Sphere model - smallest unit of matter (no protons, neutrons or electrons present)

Question 17

What was Thomsons model of the atom?

Answer 17

Plum pudding model.

Electrons embedded in positively charged matter.

Cathod ray tube experiemnt.

Question 18

What was Rutherfords model of the atom?

Answer 18

Nuclear model.

Gold foil experiment - some +ve alpha particels were deflected at an angle and did not pass straight through.

Small positive nucleus surrounded by -ve electrons.

Question 19

What was Bohrs model of the atom?

Answer 19

Planetary model.

Small positively charged nucleus, negative electrons move in fixed orbits (shells) around the nucleus.

Question 20

What is the quantum mechanical model of the atom?

Answer 20

Small positively charged nuceleus, negative electrons localised into orbits (electron clouds) around the nucleus.

(Based on work by Heisenberg, deBroglie and Schrodinger)

Question 21

Who discovered the presence of new uncharged particles (neutrons) in the nucleus?

Answer 21

Chadwick

Question 22

How did Rutherfords gold foil experiment disprove Thomsons model of the atom?

Answer 22

It showed that there was a positive nucleus that deflected the positive alpha particles.

Question 23

How would you calculatte the relative atomic mass of Chlorine using the mass and abundance of its isotopes?

HIGHER only

Answer 23

Chlorine’s Ar of 35.5 is an average of the masses of the different isotopes of chlorine.

The relative atomic mass of an element is a weighted average of the masses of the atoms of the isotopes.

Chlorine has two isotopes: 35Cl and 37Cl. In any sample of chlorine, 75 per cent of the atoms are 35Cl and the remaining 25 per cent are 37Cl.

Relative atomic mass (Ar) = (35x75) + (37x25) /100

Question 24

What does Ar stand for?

Answer 24

Relative atomic mass