Test Flashcards
1
Q
Define a compound
A
A pure substance that can be simplified. They are made up of two or more DIFFERENT elements chemically combined in a fixed ratio
2
Q
Define a molecule
A
A molecule is 2 atoms (can be the same or different) that are chemically bonded together
3
Q
Define a mixture
A
A mixture is impure and consists substances that are not chemically joined and not in a fixed ratio
4
Q
Name the 7 properties of metals
A
- lustrous fresh surface
- good conductors of electricity
- good conductors of heat
- malleable
- ductile
- solid and room temp
- relatively dense
5
Q
Proton - state where it is found, charge and size
A
In nucleus (therefore a nucleon) Positive charge Relatively large (1amu)
6
Q
Neutron- state where it is found, charge and size
A
In nucleus (therefore a nucleon) Neutral charge Relatively large (1amu)
7
Q
Electron- state where it is found, charge and size
A
In orbit in shells outsider of atom Negative charge Relatively small (0amu)
8
Q
Define a physical change
A
Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. A change in state, no new substance is made
9
Q
Define a chemical change
A
A chemical change occurs when a substance combines with another to form a new substance. They are difficult to reverse. Reactant =products
10
Q
Characteristics of a physical change
A
Change in colour, temperature, state, shape and volume
11
Q
Characteristics of a chemical change
A
Change in colour, temperature, odor/smell, production of light, bubbles, precipitate
12
Q
Solid to a liquid
A
Fusion
13
Q
Solid to a gas
A
Sublimation
14
Q
Gas to solid
A
Deposition
15
Q
Gas to liquid
A
Condensation
16
Q
Liquid to solid
A
Solidification
17
Q
Liquid to gas
A
Vapourisation
18
Q
Define an ion
A
An ion is an atom that has gained or lost on or more electrons.
19
Q
Name given to a positive ion
A
Cation
20
Q
Name given to a negatively charged ion
A
A ion
21
Q
The periodic table is a list of elements in order of increasing ________
A
Atomic numbers
22
Q
The symbol for atomic number
A
Z
23
Q
Symbol for number of neutrons
A
N
24
Q
What does the atomic number show?
A
How many protons and electrons in an atom
25
Symbol for atomic mass number
A
26
What is the atomic mass number?
The number of protons and neutrons (number of nucleons)
27
What is an isotope?
Isotopes are atoms of the same element (same proton number) but with different atomic masses (different neutron number)
28
What is the density formula?
D= M divided by V
29
Define the electronic structure
1st shell = 2
2nd shell = 8
For the first 20 elements, the 3rd shell appears to be full with 8 electrons
30
Name the properties of group 1 elements
All very reactive metals
Known as the alkali metals
They react violently with water e.g sodium
31
Name the property of group 2 elements
All are reactive metals
32
Name the properties of group 7 elements
All very reactive
Non-metals
All are found in diatomic molecules
33
Name the properties of group 8 elements
Are very non reactive
Are caller the noble gases
Have a full Valence shell
34
Define an ionic bond
Ionic bonds form following a transfer of electronics between atoms resulting in the formation of ions.
They bond with atoms on the opposite side of the periodic table
35
Define a covalent bond
Covalent bonds form when electrons are shared between atoms. When the atoms both need to gain electrons to complete their valency shells.
36
Groups in a periodic table refer to
The number of electrons in the valency shell.
| E.g. Group 5 have 5 electrons in the outer shell
37
List the properties of acids
```
Have a sour taste
Change litmus from blue to red
Conduct an electric current
Corrode most metals
React with carbonates
Neutralise bases
```
38
Name 3 strong acids
Hydrochloride acid, sulfuric acid and nitric acid
39
Name 3 weak acids
Acetit acid, carbonic acid, Citric acid
40
List the properties of bases
A bitter taste
Change colour of red litmus to blue
Conduct an electric current
Have a slippery feel
41
Name some common alkalis (bases)
Sodium hydroxide NaOH
Potassium hydroxide KOH
calcium hydroxide Ca(OH)2
42
An alkali is any substance that produces ______ in water
OH- ions
43
an alkali has a ph of
More than 7
44
A base will ______ an acid
Neutralise
45
Alkalis are ______ and _______ substances
Alkalis are HARMFUL and CORROSIVE substances
46
List the properties of an ionic compound
```
Made up of both + and - ions
Solid at room temp
Have high melting points
Dissolve in water to form aqueous solutions
Conduct electricity
```
47
Ionic compounds usually form ______ of positive and negative ions rather than individual molecules
Lattices
48
What is a lattice?
A lattice is an ordered structure of ions held together by the electrostatic attraction between + and - ions
49
What is a bonding electron
The name given to the shared electron in the covalent compound
50
Characteristics of covalent compounds are
Low melting points, as the attraction between molecules is weak
Generally do not conduct electricity bc the aren't made up of ions
insoluble in water
51
What is a chemical formula
A chemical formula is a set of symbols showing the elements present in the compound and shows their ratio
52
How is a valency of an element determined?
The Valencia determined by the number of electrons and element wants to gain or lose
53
Covalent bonds form between elements that are ------ on the periodic table
Close together on the right hand side of the periodic table
54
Mono means
1
55
Di means
2
56
Tri means
3
57
Tetra means
4
58
Pent means
5
59
Define an element
A pure substance that cannot be simplified. Are made up of one type of atom only.
60
Name the 2 liquids in the periodic table
Mercury and bromine
61
Name the 6 semi metals in the periodic table
Silicon, germanium, arsenic, antimony, selenium and tellurium
62
Name the 11 gases in the periodic table
Hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, radon
63
Describe the dalton model
Thought atoms were hard indivisible spheres
64
Describe the Thomson model
Though that the whole atom was + charged, with - electrons embedded in it like a plum pudding
65
Describe the Rutherford model
He was the first to discover the nucleus, and that electrons orbited around. Only flaw was that the electrons would lose energy and special inwards
66
Describe bohrs model
Had the same as rutherfords, only that electrons could only exist in specific shells with a certain amount of energy. Also explained why they didn't special inwards
67
Describe chadwicks model
Chadwick is the model we use today
| He found that the nucleus contained neutrons
68
Describe aristotles model
Thought that everything was made up of earth, fire, water and air composed of different ratios
69
What is a binary compound
A compound of 2 elements. The 1st one being the metal involved, the 2nd is the name of the non metal - ending in ide
70
What is an ionic compound
A compound where ions are held together in a structure by electrostatic forces
71
What is a covalent compound
Covalent compounds form between 2 or more NON METALS. The atoms share electrons to gain a full outer shell
72
Metal + oxygen =
Metal oxide
73
Metal + acid =
Salt + hydrogen
74
Metal oxide + acid =
Salt + water
75
Alkali + acid =
Salt + water
76
Metal carbonate + acid =
Salt + carbon dioxide + water
77
Very active metal + water =
Metal hydroxide + hydrogen
78
Define an acid
An acid is a compound containing hydrogen that gives free hydrogen ions in solution
79
Define a base
A base is a compound that neutralises an acid
80
Define an alkali
An alkali is a soluble base. They give free hydrogen ions in solutions
81
Define a salt
A salt is the IONIC compound formed when the hydrogen of an acid is replaced by a metal ion
82
Chemical reactions that absorb energy are called
Endothermic - temp gets colder
83
Chemical reactions that produce energy are called
Exothermic - get warmer
84
Define the term valency
The number of un paired electrons in an atoms outermost shell
85
What is a polyatomic ion?
An ion containing more than one atom
86
Define pH
Ph means potential hydrogen. It is a measure of the acidity or alkalinity of a solution
87
Define diatomic molecule and explain why they form
A diatomic molecule forms via a covalent bond, as both want to gain more stability (full valence shell)
88
What is a homonuclear diatomic molecule
A homonuclear diatomic molecule is the covalent bond of two SAME elements. Each atom in the molecule has an equal electro negativity
89
What is a heteronuclear atomic molecule
A heteronuclear diatomic atom consists of 2 DIFFERENT atoms- thus different in electro negativity. They have polar covalent bonds
