Key Concepts In Chemistry Flashcards
1
Q
What does (s) mean
A
Solid
2
Q
What does (l) mean
A
Liquid
3
Q
What does (g) mean
A
Gas
4
Q
What does (aq) mean
A
Aqueous - dissolves in water
5
Q
What is the formula for water
A
H20
6
Q
What is the formula for carbon dioxide
A
CO2
7
Q
What is the formula for chlorine
A
Cl2
8
Q
What is the formula for ammonia
A
NH3
9
Q
What is the formula for hydrogen
A
H2
10
Q
What is the formula for oxygen
A
O2
11
Q
What is the ionic formula for ammonium
A
NH4+
12
Q
What is the ionic formula for nitrate
A
NO3-
13
Q
What is the ionic formula for sulfate
A
SO42-
14
Q
What is the ionic formula for hydroxide
A
OH-
15
Q
What is the ionic formula for carbonate
A
CO32-
16
Q
What is a hazard
A
Anything that has the potential to cause harm or damage
17
Q
What is a risk
A
the probability of someone (or something) being harmed if they are exposed to the hazard
18
Q
What are the 3 subatomic particles
A
Protons, neutrons and electrons
19
Q
What are the properties of protons
A
Heavy and positively charged
20
Q
What are the properties of electrons
A
Heavy and neutral
21
Q
What are the properties of neutrons
A
Hardly any mass and are negatively charged
22
Q
Describe the nucleus of an atom
A
In the centre of an atom
Contains protons and neutrons
Has a positive charge because of the protons
It is where almost all of the atoms mass is
It is tiny compared to the overall size of the atom
23
Q
Describe the electrons of an atom
A
Move around the nucleus in electron shells
Negatively charged
Tiny but their shells cover a lot of space
The size of their shells determines the size of the atom
They have a tiny mass
24
Q
Describe the properties of atoms
A
Have the same number of protons as electrons
They are neutral (no charge)
The charge on the electrons is the same size as the charge on the protons but opposite so the charges cancel out
25
What does the nuclear symbol of an atom tell you
Its mass number and atomic number
26
What does the atomic number tell you
How many protons an atom has
27
What does the mass number tell you
The total number of protons and neutrons
28
What are isotopes
Different forms of the same element, which have the same number of protons but a different number of neutrons
Same atomic number but different mass numbers
Eg. Carbon-12 and Carbon-13
29
Who made the first periodic table
Dimitri Mendeleev
30
What are the electron shell rules
2,8,8 and the lowest energy levels are always filled first
31
What are ions
Charged particles that can be single atoms or groups of atoms
32
What is an anion
A negative ion
33
What is a cation
A positive ion
34
How do negative ions form
When atoms gain electrons
35
How do positive ions form
When atoms lose electrons
36
What groups are most likely to form ions
Group 1, 2, 6, 7
37
What are ionic compounds made up of
A positively charged part and a negatively charged part
38
What is the overall charge of any ionic compound
Zero
39
What is an ionic bond
When a metal and a non-metal reacts together.
The metal loses electrons to form a positive ion and the non-metal gains electrons to form a negative ion.
These are strongly attracted to each other with an electrostatic force
40
What do dot and cross diagrams show
The arrangement of electrons in an atom or ion
41
What do ionic compounds always have
Giant ionic lattice structures
42
What are the properties of ionic compounds
High melting and boiling point
Solid ionic compounds cannot conduct electricity
Melted ionic compounds can conduct electricity
Dissolve easily in water
43
Why do ionic compounds have high melting and boiling points
Due to their strong attraction between the ions. It takes a large amount of energy to overcome this attraction
44
Why don’t solid ionic compounds conduct electricity but melted ionic compounds do
Because in a solid, the ions are fixed in place and cant move but when melted, the ions are free to move and will carry an electric current
45
Why do ionic compounds dissolve easily in water
The ions separate and are free to move in the solution so they’ll carry an electric current
46
What are the advantages of showing ionic compounds in 2D representations
They are great at showing what atoms something contains and how the atoms are connected
47
What are the disadvantages of 2D representations of ionic compounds
They don’t show the shape of the substance and they don’t give you any idea about the sizes of the atoms
48
What are the advantages of a dot and cross diagram
They are useful for showing how compounds or molecules are formed and where the electrons in the bonds or ions came from
49
What are the disadvantages of dot and cross diagrams
They don’t usually show anything about the size of the atoms or ions or how they are arranged
50
What are the advantages of 3D models showing structures
They show the arrangement of atoms
51
What are the disadvantages of 3D models showing structures
They only show the outer layer of a substance
52
What are the advantages of a ball and stick model
Helps to visualise structures as they show the shape of the lattice or molecule in 3D
They’re more realistic
53
What are the disadvantages of ball and stick models
They don’t show the correct scales of the atoms or ions
54
What is a covalent bond
A strong bond when a pair of electrons is shared between two atoms
55
What are simple molecular substances made up of
Molecules containing a few atoms joined by covalent bonds
56
What do you need to do to melt or boil a simple molecular compound
Break the feeble intermolecular forces and not the covalent bonds
57
Do molecular compounds conduct electricity and why
No because they haven’t got any free flowing electrons or ions
58
What are the properties of giant covalent structures
Strong covalent bonds between each atom
High melting and boiling point - lots of energy needed to break the bonds
Don’t contain charged particles - don’t conduct electricity
Aren’t soluble in water
59
What are 3 examples of carbon-based giant covalent structures
Diamond
Graphite
Graphene
60
What is diamond made up of
Carbon atoms that each form 4 covalent bonds
61
Does diamond have a high or low melting point
High
62
Is diamond hard or soft, why
Hard because the strong covalent bonds hold the atoms in a rigid lattice structure
63
Does diamond conduct electricity
No because it has no free electrons or ions
64
In graphite, how many covalent bond does a carbon atom form, what does it create
3, creating sheets of carbon atoms arranged in hexagons
65
Is graphite hard or soft, why?
Soft and slippery because there aren’t any covalent bonds between the layers so they’re held together weakly and free to move over each other
66
Can graphite conduct electricity
Yes as only 3 out of 4 electrons are used in bonds so each carbon atom has 1 electron that’s delocalised (free)
67
What is the structure of graphene
1 layer of graphite
| A sheet of carbon atoms joined together in hexagons
68
Are the electrons in the outer shell of metal atoms localised or delocalised
Delocalised
69
What is metallic bonding
The forces of attraction between the positive metal ions and the shared negative electrons hold the atoms together in a regular structure.
70
What is the relative formula mass (RFM)
The relative atomic masses of all the atoms added together
71
What does the empirical formula of a compound tell you
The smallest whole number ratio of atoms in a compound
72
How do you calculate the molecular formula
Add the empirical formula and the relative formula mass
73
What is a mole
The name given to a certain number of particles
74
What is a mole equal to
A number called Avogrado’s constant
75
What is the number of Avogrado’s constant
6.02 x10 to the power of 23
76
Why is Avogrado’s constant useful
Because when you get the number of atoms or molecules, of any element or compound, then they weigh the same number of grams as the RAM/RFM of the element or compound
77
What is the equation for the number of moles
Number of moles = mass in g (of element or compound) / RFM of compound or RAM of element
78
What is the formula triangle involving mass, moles and RFM
Mass
—————-
Moles x RFM
79
What is the equation for concentration
Concentration = mass of solute / volume of solution
80
When do reactions stop
When all of one reactant is used up
81
What is the limiting reactant
The reactant that is used up in the reaction
