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Chemistry GCSE > Key Concepts (Papers 1 & 2) > Flashcards

Key Concepts (Papers 1 & 2) Flashcards

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1
Q

What was the plum pudding model?

A

Negatively charged electrons in a circle of positively charged ‘pudding’

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2
Q

Why was the plum pudding model wrong?

A

Because scientists like Rutherford realised the electrons around the nucleus would be attracted to it and therefore pulled into the centre causing it to collapse.

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3
Q

What did the gold foil experiment show?

A

That when they fired positively charged electrons at a extremely thin sheet of gold foil, the particles were expected to go straight through. However, many particles bounced back which showed the must be a dense nucleus in the centre.

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4
Q

How was the refined Bohr model better than the plum pudding model?

A

They arranged the electrons in wheels around the Nucleus so it doesn’t collapse

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5
Q

What charge does the Nucleus have?

A

Positive

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6
Q

Why is the refined Bohr model accepted by most scientists at the time?

A

Because it was supported by many experiments and it helped explain lots of other scientists observations at the time. It was pretty close to our currently accepted version of the atom.

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7
Q

What is the relative mass of neutrons electrons and protons?

A

Proton: 1
Neutron: 1
Electron: 0.0005

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8
Q

What does the atomic number mean?

A

Tells you how many protons the atom has.

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9
Q

What does the mass number tell you?

A

Tells you the total number of protons and neutrons in the atom.

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10
Q

Is the atomic mass the bigger or smaller number?

A

Bigger and hence the atomic number is the smaller number.

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11
Q

What is an isotope?

A

two forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties.

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12
Q

What is the mass number equal too?

A

The protons add neutrons.

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13
Q

What is the number of electrons equal too?

A

The number of protons.

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14
Q

How do find out the number of neutrons?

A

The mass number - the atomic number(number of protons)

big-small number

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15
Q

What is relative atomic mass?

A

The relative atomic mass is a measure of the mass of one atom of the element. compared to carbon at 12

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16
Q

How do you calculate relative FORMULA mass?

A

Add together the Ar (atomic mass) of all the elements in the compound but remember to take in the account the number of times it appear.

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17
Q

How to calculate average ram (relative atomic mass)

average of all isotopes

A

(mass no. of isotope x abundance amount of that isotope)) + (mass no. of other isotope x abundance that isotope)

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18
Q

What is covalent bonding?

A

A covalent bond is an intramolecular interaction in which two atoms share electrons to fill their outer electron shell.

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19
Q

What is an ion?

A

an atom or group of atoms that has a charge. an atom gains a charge by losing or gaining an electron. Electrons are negative so if you lose an electron you gain a positive charge.

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20
Q

What is ionic bonding?

A

Ionic bonding occurs between positive and negative ions, which attract each other and bind together to form ionic compounds. One atom might give an electron to and another atom which needs another electron to complete its outer shell For example, sodium chloride consists of Na+ ions and Cl- ions bound together through electrostatic attraction

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21
Q

What structure does a compound bonded through ionic bonding have?

A

a giant ionic lattice with oppositely charged ions

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22
Q

Features of a giant ionic lattice?

A

Bonded through ionic bonding. very strong / high melting point due to strong electrostatic forces of attraction. Can only conduct electricity when molten/ in solution because otherwise they are too tightly packed when solid.

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23
Q

What are the features of simple molecular structures?

A

The atoms are held together by strong covalent bonds however the intermolecular forces holding the molecules together are week meaning it does not require much energy to overcome them so they have a low melting/boiling point. They do not conduct electricity, this is because they do not have any free electrons or an overall electric charge.

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24
Q

What are the features giant covalent bonds?

A

Giant covalent structures contain many atoms joined together by very strong covalent bonds to form a giant lattice. They have high melting and boiling points. Graphite and diamond have different properties because they have different structures. Graphite conducts heat and electricity well because it also has free electrons in which electricity can pass through.

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25
Q

What are the features of metallic substances?

A

Delocalised negative electrons and positive metal ions have strong forces of attraction.
They have a high melting and boiling point because of strong electrostatic forces of attraction.
They conduct Electricity in any state because of the delocalised electrons.

26
Q

How did Mendeleev organise the periodic table?

A

By order of increasing atomic mass. (left gaps) and sometimes swapped elements around so they were in groups of similar chemical properties.

27
Q

xxx

A

Tentacion

28
Q

Why did Mendeleev leave gaps in the periodic table?

A

left gaps in his periodic table because the properties of known elements predicted other, as-yet-undiscovered, elements in these locations. As Mendeleev organized his periodic table, he recognized that these gaps would be filled as future scientists identified new elements.

29
Q

How are elements arranged in periods in the current periodic table?

A

The periods are columns of similar chemical properties. If they are in period 1 then they will have 1 electron on their outer shell. if they are in period 7 they will have 7 electrons in their outer shell.

30
Q

what are the stages of water purification?

A

1) sedimentation tank
2)filtration tower
3) disinfectant tank- (chlorine
(see a diagram for more depth)

31
Q

What happens in the sedimentation tank?

A

Larger items are allowed to settler at the bottem.

32
Q

what happens in the filtration tower?

A

The water runs through a fine filter to stop the smaller solids like leaves and dirt getting through.

33
Q

what happens in the disinfectant tank?

A

Chlorine is added to the drinking water to sterilise it. The chlorine kills microbes - including microbes that cause potentially-fatal diseases.

34
Q

How do you draw the equation for ionic bonded compounds?

A

With a dot cross diagram for the starting materials and then the products shown as a dot cross diagram with brackets and their respective charges.

35
Q

Sam

A

loves caitlin

36
Q

What is a cation?

no Sam, not caitlin

A

a positive ion

37
Q

What is an anion?

A

A negatively charged ion

38
Q

What is a covalent bond?

A

When a pair of electrons is shared between two atoms

  • strong
  • non metal atoms
39
Q

What is Empirical formulae?

A

The simplest whole number ration of atoms of each element in a compound (work out in a table/list not a formula)
divide mass of each element by the Ar of that element and the divide that number by the smallest of the two answers and right as a ration e.g 1:3

40
Q

What is Ar?

A

relative atomic mass (mean mass of atoms of an element which take into account abundance)

41
Q

What is good and bad about dot and cross diagrams?

A

good
-clear
bad
-suggest the dots and crosses are different but thy are not

42
Q

what is good and bad about the metallic model?

A 
good
-shows the metal ions held in a lattice
-shows why it conducts electricity
bad
-doesn't show how they vibrate
43
Q

What is a mole?

A

A chemical quantity referring to the amount of a substance

One mole of a compound is the same as their formula mass

44
Q

How do you calculate the amount mol(e) from the mass?

A

amount = mass/Ar
mass
amount Ar

if in a compound us Mr

45
Q

What is Mr?

A

formula mass

46
Q

How do you work out the Rf value from paper chromatography?

A

Distance moved by spot/distance moved by solvent

47
Q

What is the mobile phase?

A

The solvent

48
Q

What is the stationary phase?

A

The paper

49
Q

How do you work out moles?

A

Mass/formula mass

50
Q

How to work out the ratio or empirical formula for two substances

A 
Write is out, write mass used below it, write atomic mass below that divide mass by atomic mass to find moles and then write as a ratio ( can divide by smallest answer
Na + Cl2
2.3g      10.4g
23.         35.5 x 2 
0.1.    :     0.15
1         :      1.5
2.       :        3
51
Q

How to work out concentration in g/dm3

A

Mass of solute/volume of solute in dm3

1 dm3 = 1000 cm3

52
Q

Why did mandeleeve leave gaps in his periodic table?

A

Because he predicted elements which haven’t been discovered

53
Q

Why did mandeleeve swap some elements about?

A

So that they were with other elements better suited to their chemical properties

54
Q

What is deposition?

A

When a gas turns straight into a solid

55
Q

What is sublimation?

A

Turning straight from a solid into a gas

56
Q

Why does the temperature stay the same when changing state?

A

Because all added energy is being used in braking bonds to change state

57
Q

What are the properties of simple molecular substances?

A

strong covalent bonds

  • just a few joined atoms
  • low metling/boiling bonds
  • don’t conduct electricity unless dissolved in a soloution
58
Q

What are the properties of a giant molecular substance?

A
  • strong covalent bonds
  • non metals
  • high melting/boiling point
59
Q

Why do metals conduct electricity?

A

delocalised electrons

60
Q

What is an isotope?

A

They have the same number of protons but different number of NUETRONS

Chemistry GCSE (10 decks)

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