Elements , Compounds And Atoms

Question 1

What is an element?

Answer 1

A substance made up of only one type of atom that cannot be broken down into anything simpler

Question 2

What is a compound?

Answer 2

A substance containing two or more elements that are chemically bonded together in a fixed ratio

Question 3

What is a mixture?

Answer 3

A substance containing two or more elements or compounds (in a variable ratio) not chemically combined

Question 4

What is a molecule?

Answer 4

two or more atoms chemically joined together

Question 5

why does sodium chloride not fizz when added to water?

Answer 5

• its a compound
• it has different properties to sodium
• it is a completely different substance

Question 6

What is an electron ?

Answer 6

A subatomic particle found in shells around the nucleus

Question 7

What are the characteristics of an electron?

Answer 7

-negatively charged
-mass of virtually 0
-found in shells
-can be lost or gained in reactions

Question 8

What is an atom?

Answer 8

The smallest part of a substance that cannot be broken down chemically

Question 9

What is an ion?

Answer 9

An atom or a group of atoms that has a net electric charge due to losing or gaining electrons

Question 10

List the different properties of metal

Answer 10

-shiny
-high melting/boiling points
-malleable
-ductile
-good electrical conductors
-good thermal conductors

Question 11

What is the relative mass and relative charge of a proton?

Answer 11

Relative mass = 1
Relative charge = +1

Question 12

What is the relative mass and relative charge of a neutron?

Answer 12

Relative mass = 1
Relative charge = 0

Question 13

What is the relative mass and relative charge of an electron?

Answer 13

Relative mass = approx 0 (1/1840)
Relative charge = -1

Question 14

What is the atomic number?

Answer 14

The number of protons and (if neutral) electrons in an atom

Question 15

What is the mass number?

Answer 15

The sum of the protons and neutrons

Question 16

what particle is used to determine what element a substance is?

Answer 16

proton

Question 17

What did James Chadwick discover?

Answer 17

Neutrons (NOT protons)

Question 18

Describe the plum pudding model

Answer 18

The plum pudding model is the idea that an atom is a sphere of positive charge with negatively charged electrons scattered through it (using a cathode ray tube)

Question 19

What did Niels Bohr discover?

Answer 19

Electron shells (energy levels)

Question 20

What did Ernest Rutherford discover?

Answer 20

The nuclear model - atoms have a tiny positive nucleus with negatively charged electrons scattered outside it taking up most of its volume (using alpha particles)

Question 21

What are isotopes?

Answer 21

Isotopes are atoms of the same element which have the same number of protons but a different number of neutrons

Question 22

What is the relative atomic mass?

Answer 22

The average mass of an atom (compared to 1/12th the mass of a carbon atom)

Question 23

How do work out the relative atomic mass?

Answer 23

By multiplying the mass number of the isotopes with its abundance (in percentage) and dividing it by 100

Question 24

gallium(Ga) is in Group 3 of the periodic table - what is the formula of a gallium ion?

Answer 24

Ga3+

Question 25

would would oxygen be an unsuitable gas to use in a light bulb?

Answer 25

because its too reactive and would react with the metal

Question 26

What is the electron arrangement in the energy levels (shells)

Answer 26

2,8,8

Question 27

What is the group number equal to?

Answer 27

The numbers of electrons in the outer shell (column)

Question 28

What is the period number equal to?

Answer 28

The number of shells (row)

Question 29

what is the connection between metals , non-metals and electron configuration?

Answer 29

-metals have less than 4 electrons in their outer shell -non-metals have 4 or more electrons in their outer shell

Question 30

Which group in the periodic table contains the most reactive metals and why?

Answer 30

Group 1 (the alkali metals) They only have to lose one electron to gain a full outer shell

Question 31

why do elements get more reactive as you go down the periodic table

Answer 31

- the outer electron goes further from the nucleus - the atoms get larger - the attraction between the nucleus and the outer electron gets weaker - so the electron is more easily lost

Question 32

What group in the periodic table contains the most reactive non - metals?

Answer 32

Group 7 They only have to gain one electron to gain a full outer shell

Question 33

What are elements in group 7 called?

Answer 33

Halogens

Question 34

What are elements in group 0 called and how does their reactivity change?

Answer 34

Noble gases They only have to gain one electron to gain an outer shell

Question 35

what are the elements found in the central block of the periodic table between group 2 and group 3 called?

Answer 35

transition metals

Question 36

what is the test for hydrogen?

Answer 36

squeaky pop test

Question 37

why can hydrogen be placed in either Group 1 or Group 7?

Answer 37

because it only has 1 electron meaning it could lose 1 to go in Group 1 or gain 1 to go in Group 7

Question 38

what is an exothermic reaction?

Answer 38

a chemical reaction in which energy is released to the surroundings making it warmer

Question 39

what is a positive ion and how is it formed?

Answer 39

a charged particle formed when an atom loses electrons to become positively charged (a cation)

Question 40

what is a negative ion and how is it formed?

Answer 40

a charged particle formed when an atom gains electrons to become negatively charged (an anion)