Topic 1- Key Concepts In Chemistry Flashcards Preview

Chemistry > Topic 1- Key Concepts In Chemistry > Flashcards

Flashcards in Topic 1- Key Concepts In Chemistry Deck (53):
1

On the left hand side of an equation are...

The reactants

2

On the right hand side of an equation are

The products

3

State symbols

(s) - solid
(l) - liquid
(g) - gas
(aq) - aqueous, dissolved in water

4

Ammonia formula
Chlorine formula

NH3
Cl2
(The numbers are smaller than the letters and sit below the line when written)

5

Ammonium, Nitrate, Sulfate, Hydroxide and Carbonate
Formula

NH4 +
NO3 -
SO4 (2-)
OH -
CO3 (2-)
(The numbers are smaller than the letters and sit below the line when written)

6

Oxidising
Harm, example and symbol?

Provides oxygen which allows other material to burn more fiercely
Eg. Liquid oxygen
Symbol- circle with flame on top

7

Harmful
Harm, example and symbol?

Can cause irritation, reddening or blistering of the skin
Eg. Bleach
Symbol- an explanation mark

8

Environmental hazard
Harm, example and symbol?

Harmful to organisms and to the environment
Eg. Mercury
Symbol- a dead tree and dead fish

9

Highly flammable
Harm, example and symbol?

Catches fire easily
Eg. Petrol
Symbol- a line with a flame above it

10

Toxic
Harm, example and symbol?

Can cause death by for example swallowing, breathing in or absorption through the skin
Eg. Hydrogen cyanide
Symbol- skull and cross bones

11

Corrosive
Harm, example and symbol?

Destroys materials including living tissues (like eyes and skin)
Eg. Concentrated sulfuric acid
Symbol- two test tubes pouring a substance which is decaying a hand and a block object

12

John Dalton (19th century) described atoms as...

Solid spheres and said that different spheres made up different elements

13

In 1897 J J Thomson had a new theory called the...

Plum pudding model
His measurements of charge and mass from experiments concluded that an atom must contain even smaller, negatively charged particles- electrons.

14

Rutherford (1909) had a theory of...

The atom containing mostly empty space and having a positively charged nucleus at the centre

15

Bohr model showed...

All electrons are contained in a shell
Electrons can only exist in fixed orbits, or shells, nowhere in between
Each shell has a fixed energy

16

Subatomic particles and their properties

Protons - relative charge is positive (+1) and a relative mass of 1
Neutrons - relative charge is neutral (0) and a relative mass of 1
Electrons - relative charge is negative (-1) and a relative mass of 0.00005

17

Atoms are neutral because...

The number of electrons is equal to the numbers of protons

18

In an ion the number of protons...

Does not equal the same number of electrons
Therefore the ion has a charge

19

The atomic number (bottom number) tells you...

How many protons an atom has
(So for a neutral atom the number of electrons will also equal the atomic number)

20

Mass number (top number) tells you...

The total number of protons and neutrons in an atom

21

To work out the number of neutrons in an atom you...

Mass number - atomic number = neutron number

22

Isotopes contain the same numbers of .... but a different number of ....

Same number of Protons
Different number of Neutrons

23

Isotope have the same... but different...

Same atomic number
Different mass number

24

The relative atomic mass of an element is the average mass of one atom of the element, compared to...

1/12 of the mass of e atom of carbon-12

25

How to work out relative atomic mass from isotopic abundance’s

Multiply each relative isotopic mass by its isotopic abundance and add up the results
Then divide by the sum of the abundance’s- if the abundance’s are given as a percentage, this will be 100
(See bottom of page 17 in revision guide for example)

26

What did Dmitri Mendeleev’s periodic table look like?

Sorted into groups by properties (and the properties of their compounds)
Ordered them in atomic mass and realised there was a pattern- he could put chemicals with similar properties in columns
Left gaps for undiscovered elements and predicted their properties


27

Some of Mendeleev’s order in the periodic table were wrong because...

Of the presence of isotopes

28

Modern periodic table shows...

Elements in order of ascending atomic number (fit Mendeleev’s pattern)
Elements with similar chemical properties form columns called groups
The group to which to the element belongs corresponds to the number of electrons it has in its outer shell
Periods (rows) represent another full shell of electrons, so the period to which an element belongs to corresponds to the number of shells of electrons it has

29

Electron configurations can be worked out from...

Which period and group the element is in
Period- how many shells there are
Group- how many electrons are present in the outer shell

30

Ions are ... particles (can be single atoms or groups of atoms)

Charged

31

Ions form when...

Atoms lose or gain electrons

32

Negative ions are also called...
And form when...

Anions
Atoms gain electrons

33

Positive ions are also called...
And are formed when...

Cations
Atoms lose electrons

34

Which groups are most likely to form ions

Groups 1 and 2 - metals
They would lose electrons to form positive ions

Groups 6 and 7 - non metals
They would gain electrons to form negative ions

35

Ionic bonding is when... reacts with ...

A metal reacts with a non metal
The metal atom loses an electron to form a cation and the non metal gains those electrons to form an anion
Strongly attracted to each other by electrostatic forces

36

How would you show an how an ionic compound is formed in a diagram

Dot and cross diagram

37

Ionic compounds properties?
(5 to list)

1. Giant ionic lattice structures
2. Strong electrostatic forces of attraction between oppositely charged ions, in all directions
3. High melting and boiling points- large amounts of energy needed because of the large structure
4. Solid ionic compounds don’t conduct electricity (ions are fixed in place) by it when melted they do (ions are free to move)
5. Many dissolve in water, ions separate and are all free to move

38

2D representation
(3 advantages)
(2 disadvantages)

+ display of molecules is simple
+ show what the atoms contain
+ show how the atom is connected

- don’t show shape of the substance
- don’t give any idea of sizes of the atoms

39

Dot and cross diagram
(2 advantages)
(2 disadvantages)

+ show how molecules or compounds are formed
+ where the electrons in the bonds or ions came from

- don’t show size of the atoms or ions
- don’t show the arrangement of an atom or ion

40

3D models
(1 advantages)
(1 disadvantages)

+ show arrangement of ions

- only show the outer layer of the substance

41

Ball and stick models
(2 advantages)
(2 disadvantages)

+ help visualise structures, because they are shown in the shape of the lattice or molecule in 3D
+ more realistic than 2D drawings

- can be misleading, because it makes it look like there are big gaps between the atoms, whereas that’s where the electron clouds interact
- don’t show correct scales of the atoms or ions

42

Covalent bonding is...

Where a pair of electrons is shared between two atoms

43

Properties of simple molecular substances?
(5 to list)

1. Very strong covalent bonds
2. Forces of attraction are weak between these molecules
3. Melting and boiling points are low because you only need to break the intermolecular forces not the covalent bonds
4. Most are gases and liquids at room temperature
5. Don’t conduct electricity because there are no free electrons or ions

44

As simple molecular substances get bigger the strength of the intermolecular forces... which means ... energy is needed to break the bonds and so the melting and boiling points...

1. Increases
2. More
3. Increases

45

Polymers are molecules made up of long chains of ...
Formed when lots of small molecules called ... join together

Covalently bonded carbon atoms
Monomers

46

Giant covalent structures properties?
(4 to list)

1. Very high melting and boiling points
2. Bonded by strong covalent bonds
3. Mostly don’t conduct electricity
4. Aren’t soluble in water

47

Diamond properties?
(4 to list)

1. Network of carbon atoms that each form 4 covalent bonds
2. High melting point (because of the strong covalent bonds)
3. Rigid lattice structure (because of the strong covalent bonds) making diamond really hard, it’s used to strengthen cutting tools
4. Doesn’t conduct electricity- no free electrons

48

Graphite properties?
(4 to list)

1. Each carbon only forms 3 covalent bonds (creating sheets of carbon arranged in hexagons)
2. No covalent bonds between layers, free to move over each other- meaning graphite is ideal as a lubricating material because it’s soft and slippery
3. High melting point
4. Each carbon atom has one electron ( because they only form 3 bonds out of 4) which can delocalise and can move, which means it can conduct electricity

49

Graphene properties?

1. Is one layer of graphite
2. Sheet of carbon atoms joined together in hexagons
3. 2D compound, because the sheet is only one atom thick

50

Fullerenes are shaped like...
Mainly made up of ... and arranged in a ... shape
Can be used to ...... eg.....
They have a huge... and would make a great industrial...

Hollow balls of closed tubes
Carbon atoms, hexagon
Cage other molecules, eg. Deliver drugs directly to the cells in the body
Surface areas, catalysts

51

Metallic bonding...

Electrons on the outer shell are delocalised
Strong forces of attraction between the positive ions and the shared negative electrons
These forces of attraction hold the atoms together in a regular structure

52

Physical properties of metals?
(5 to list)

1. Electrostatic forces between the metal ions and the delocalised sea of electrons are very strong (needs lots of energy to be broken)
2. High melting and boiling points
3. Aren’t soluble in water
4. More dense then non metals
5. Delocalised electrons can carry electrical and thermal energy, metals are good conductors of electricity and heat

53

Non metals properties?

Can be brittle and dull looking
Lower boiling points (not usually solid at room temperature)
Don’t conduct electricity
And often have a lower density