Chapter 1,2,314 Definitions (5th year mid term)

Question 1

Element

Answer 1

Cannot be chemically broken down into simpler substances

Question 2

The law of conservation of mass

Answer 2

Matter can be neither created or destroyed in the corse of a chemical reaction

But can change from one form to another

Question 3

Cathode rays

Answer 3

Electrons

Question 4

Atomic number

Answer 4

The number of protons in the nucleus of an atom of that element

Question 5

Mass number

Answer 5

The total number of protons and neutrons in the nucleus of an atom of that element

Question 6

Isotopes

Answer 6

Atoms of the same element with the same number of protons and different numbers of neutrons

Eg. C12 C13 C14

Question 7

Relative atomic mass

Answer 7

The average mass of an atom of the element relative to 1/12 of the mass of an atom of carbon-12

Question 8

Mass spectrometer

Answer 8

Instrument that measures the masses and relative abundance’s of the isotopes of an element

Question 9

Radioactivity

Answer 9

The spontaneous decay of an unstable nucleus accompanied by the emission of radiation

Question 10

Alpha particle

Answer 10

Helium nuclei with a positive charge and little penetrating energy

Question 11

Beta particles

Answer 11

Electrons with a negative charge and greater penetrating ability than alpha particles

Question 12

Gamma rays

Answer 12

High-energy electromagnetic radiation, greater penetrating ability than beta particles

Question 13

Beta decay

Answer 13

When an isotope undergoes beta decay, it’s atomic number increases by 1 , while its mass number is unchanged

Eg
19. 19. 0
O. = F. + e
8. 9. -1

Question 14

Alpha decay

Answer 14

When an isotope undergoes alpha decay it’s atomic number decreases by 2, while it’s mass number decreases by 4

4
He
2

Question 15

Half life

Answer 15

The half life of a radioactive isotope is the time taken for half of the atoms in a sample of the isotope to decay

Question 16

Radioisotope

Answer 16

Radioactive isotope

Question 17

Rate of reaction

Answer 17

The change in concentration in unit of time of any one reactant or product

Question 18

Instantaneous rate of reaction

Answer 18

The rate at a particular point in time during the reaction

draw tangent line and find slope

Question 19

Catalyst

Answer 19

Substance that alters the rate of a chemical reaction but is chemically unchanged at the end of the reaction

Question 20

Homogeneous

Answer 20

Reactant and catalyst in same phase (solid liquid gas )

Question 21

Heterogeneous

Answer 21

Reactant and catalyst in different phases

Question 22

Phase

Answer 22

Physical state

solid liquid gas

Question 23

Autocatalysis

Answer 23

Products of a reaction catalyses its own reaction

Question 24

Activation energy

Answer 24

Minimum energy with which particles need to collide for an effective collision