chem 13.1

Question 1

what is the smallest part of an element

Answer 1

an atom

Question 2

what are elements

Answer 2

substances that only contain 1 kind of atom

Question 3

how many elements have been identified?

Answer 3

118

Question 4

how many elements occur naturally?

Answer 4

92

Question 5

can elements exist as molecules?

Answer 5

some elements exist as molecules which can be represented by a chemical formula indicating the number of atoms it contain

Question 6

3 types of element classification

Answer 6

metals, non-metals and semi metals / metalloids

Question 7

name 2 semi metals

Answer 7

boron, silicon

Question 8

how can the electrical conductivity of a semi metal increase?

Answer 8

when it is mixed with a small amount of impurity / their temperature is increased

Question 9

can semi metals conduct electricity at room temperature

Answer 9

semi metals cannot conduct electricity at room temperature

Question 10

malleable meaning

Answer 10

can be bent or pressed into different shapes

Question 11

brittle meaning

Answer 11

breaks / fractures easily when subjected to force

Question 12

ductile meaning

Answer 12

can be pulled into thin wires

Question 13

physical state at room temperature

Answer 13

metals are solid (except mercury)
non-metals are solid / gas (except bromine)

Question 14

appearance

Answer 14

metals are shiny
non-metals are usually dull (except diamond, a form of carbon)

Question 15

strength

Answer 15

metals are strong
non-metals are brittle

Question 16

melting point / boiling point

Answer 16

metals have a high bp/mp (except mercury + sodium for melting point)
non-metals usually have a low bp/mp (except diamond and graphite)

Question 17

density

Answer 17

metals have high density
non metals usually have low density

Question 18

thermal conductivity

Answer 18

metal has good conductivity
non-metals usually have poor conductivity

Question 19

electrical conductivity

Answer 19

metals are good
non-metals are poor (w/ exception of graphite)

Question 20

malleability / ductility

Answer 20

metals are good
non-metals are poor

Question 21

where is most of the mass in an atom stored

Answer 21

in the nucleus

Question 22

what is the rest of an atom usually

Answer 22

the rest of an atom is usually empty space

Question 23

how do electrons move around the nucleus

Answer 23

very fast

Question 24

what in an atom must be the same

Answer 24

the amount of protons / electrons

Question 25

what is an atomic number?

Answer 25

the number of protons in an atom

Question 26

what is a mass number?

Answer 26

the sum of the number of protons and neutrons in an atom

Question 27

why do we only take the number of protons and neutrons into account when comparing the mass of different atoms?

Answer 27

bc the relative masses of protons and neutrons are comparable to each other, while the mass of electrons is so small that it can be neglected

Question 28

where is the proton, electron and neutron located

Answer 28

proton and neutrons are located inside the nucleus, while electrons move around the nucleus

Question 29

relative mass of protons electrons and neutrons

Answer 29

protons 1 electrons negligible ~1/1800 neutrons ~1

Question 30

relative charge of proton electron neutron

Answer 30

proton +1 electron -1 neutron 0

Question 31

what are ions

Answer 31

particles carrying charge

Question 32

do atoms have electrical charge

Answer 32

atoms do not have electrical charge (they are neutral)

Question 33

how is a positive ion formed and what is its name

Answer 33

cation, formed by losing electrons

Question 34

what material tends to form positive ions

Answer 34

metals tend to lose electrons to form positive ions

Question 35

how is a negative ion formed and what is its name

Answer 35

anion, formed by gaining electrons

Question 36

what material tends to form negative ions

Answer 36

non-metals tend to gain electrons to form negative ions

Question 37

hydrogen chemical formula

Answer 37

H2

Question 38

nitrogen chemical formula

Answer 38

N2

Question 39

nitrogen chemical formula

Answer 39

N2

Question 40

oxygen chemical formula

Answer 40

O2

Question 41

ozone chemical formula

Answer 41

O3

Question 42

phosphorus chemical formula

Answer 42

P4

Question 43

sulphur chemical formula

Answer 43

S8

Question 44

hydrogen ion

Answer 44

H+

Question 45

oxygen ion

Answer 45

O2-

Question 46

fluorine ion

Answer 46

F-

Question 47

sodium ion

Answer 47

Na+

Question 48

magnesium ion

Answer 48

Mg2+

Question 49

aluminum ion

Answer 49

Al3+

Question 50

sulphur ion

Answer 50

S2-

Question 51

chlorine ion

Answer 51

Cl-

Question 52

potassium ion

Answer 52

K+

Question 53

calcium ion

Answer 53

Ca2+

Question 54

bromine ion

Answer 54

Br-

Question 55

why are atoms mostly empty space?

Answer 55

to allow the electrons to move around the nucleus

Question 56

what is the purpose of neutrons

Answer 56

to regulate the mass of the atom