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Chemistry-Zoe Brown > Topic 1 > Flashcards

Topic 1 Flashcards

1
Q

How to write an ionic equation

A
  1. anything that’s ionic and aqueous will break up into its ions in solution.so write out equation showing all aqueous ions separately
  2. to get the ionic equation,cross out anything that’s the same on both sides of the equation
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2
Q

Describe how the Dalton model of an atom changed over time because of the discovery of subatomic particles

A

Alpha particles were fired at a thin sheet of gold. The plum pudding model predicted the alpha particles would pass straight through the sheet or only be deflected slightly.though most of particles did pass straight through a few were deflected more than expected and a small number were deflected straight back. This suggested that most of an atom is made up of empty space with a positive nucleus in the centre

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3
Q

What did Bohr suggest

A

That electrons can only exist in fixed orbits/shells and not anywhere in between

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4
Q

What are the 3 subatomic particles in an atom

A
  1. protons - heavy and positively charged
  2. nucleus - heavy and neutral, makes up most of mass of atom
  3. electrons - hardly any mass and negatively charged
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5
Q

Nucleus

A
  • in the middle of the atom
  • contains protons and neutrons
  • has a positive change due to protons
  • very small compared to overall size of atom
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6
Q

Electrons

A
  • move around nucleus in electron shells
  • they’re negatively charged
  • they are tiny but shells cover a lot of space
  • size of their shell determines size of atom
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7
Q

Relative mass and relative charges for subatomic particles

A

Proton- RM = 1, RC = +1
Neutron- RM = 1, RC = 0
Electron- RM = 0.0005, RC = -1

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8
Q

Ion

A

An atom or group of atoms that has lost or gained electrons

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9
Q

Atomic number

A

Tells you how many protons (and electrons for a neutral atom)an atom has and is the bottom left number on a periodic element symbol

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10
Q

Mass number

A

Tells you the total number of protons and neutrons in an atom and is in the top right of a periodic element symbol

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11
Q

How to calculate number of neutrons

A

mass number - Atomic number

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12
Q

Isotopes

A

Different forms of the same element which have the same number of protons but a different number of neutrons

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13
Q

Relative atomic mass

A

Is the average mass of one atom of the element

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14
Q

How to work out relative atomic mass of element from relative masses and abundance’s of its isotopes

A
  • multiply each relative isotopic mass by its isotopic abundance and add up the results
  • divide by the sum of abundances (if abundances are given as percentages this will be 100)
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15
Q

Isotopic abundances

A

Different isotopes of an element occur in different quantities

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16
Q

How did Mendeleev organise his version of the periodic table

A

He sorted elements into order of atomic mass as he did a pattern appeared so he could put elements with similar chemical properties in columns

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17
Q

How did Mendeleev predict the properties of undiscovered elements

A

By looking at the properties of other elements in the same column as the gaps

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18
Q

What does the group of an element show

A

Show the number of electrons the element has in its outer shell and a group is the number across that element is on the periodic table

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19
Q

What does the period of an element show

A

How many electron shells the element has and a period is the number down the periodic table

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20
Q

Why are the elements that most readily form ions in groups 1,2,6 and 7

A
  • group 1 and 2 elements are metals so lose electrons to form positive ions
  • groups 6 and 7 are non-metals so gain electrons to form negative ions
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21
Q

Dot and cross diagrams

A

Show the arrangement of electrons in an atom or ion. Each electrons is represented as a dot or a cross. So these diagrams can show which atom the electrons in an ion originally came from

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22
Q

Ionic compound properties

A
  • giant ionic lattice structure
  • strong electrostatic forces of attraction between oppositely charged ions in all directions
  • high melting an boiling points due to strong attraction between ions so takes late amount of energy to overcome the attraction
  • solid ionic compounds don’t conduct electricity because ions are in fixed place,but if it melts ions are free to move and will carry an electric current
  • many dissolve in water, the ions separate and are all free to move in solution so they’ll carry an electric current
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23
Q

Advantages and disadvantages of 2D representations

A

Advantages -simple great at showing what atoms something contains and how many atoms are connected

Disadvantages- don’t show shape of substance and don’t give any idea about sizes of atoms in

24
Q

Advantages and disadvantages of dot and cross diagrams

A

Advantages- useful for showing how compounds or molecules are formed and where the electrons in the bonds or ions came from

Disadvantages- don’t usually show anything about size of atoms or ions or how they’re arranged

25
Q

Advantages and disadvantages of 3D models

A

Advantages- show arrangement of ions

Disadvantages- only show outer layer of substance

26
Q

Advantages and disadvantages of ball and stick models

A

Advantages- great for helping visualise structures as they show the shape of lattice and how the atoms in a substance are arranged

Disadvantages- can be misleading as they make it look like there a big gaps b tween the atoms when in reality it’s where the electron clouds interact, don’t show correct scales of atoms or ions

27
Q

Covalent bonds

A

A strong bond that forms when a pair of electrons is shared between two atoms. Result in formation of molecules

28
Q

Properties of simple molecular bonds

A
  • atoms held together by very strong covalent bonds - forces of attraction between molecules are very weak
  • low melting and boiling points because only need to break feeble intermolecular forces and not the covalent bonds
  • most are gases or liquids at room temperature
  • don’t conduct electricity because don’t contain any free electrons or ions
  • some are soluble some aren’t
29
Q

Polymers

A

molecules made up of long chains of covalently bonded carbon atoms. form when lots of small molecules called monomers join together

30
Q

Properties of giant covalent structures

A
  • all atoms bonded by strong covalent bonds
  • very high melting and boiling points as lots of energy need to break covalent bonds
  • generally don’t contain charged particles so don’t conduct electricity apart from graphite and graphene
  • aren’t soluble in water
31
Q

Examples Carbon-based Giant covalent structures: diamond

A
  • made up of a network of carbon atoms that form 4 covalent bonds
  • strong covalent bonds so has high melting point
  • strong covalent bonds hold atoms in s rigid lattice structure making diamonds really hard
  • doesn’t conduct electricity
32
Q

Examples Carbon-based Giant covalent structures: graphite

A
  • each carbon only forms 3 covalent bonds creating sheets of carbon atoms arranged in hexagons
  • aren’t covalent bonds between layers only held together weakly so they free to move over each other.this makes graphite soft and slippery so it’s and ideal lubricating material
  • high melting point
  • conducts electricity as 3 out of each carbons 4 outer electrons are used in bonds so each carbon has 1 electron that’s delocalised(free) and can move
33
Q

Fullerenes

A

molecules of carbon, shaped like closer tones/hollow balls.mainly made up of carbon atoms arranged in hexagons can also contain pentagons or heptagons. can be used to “cage” other molecules, structure forms around another atom or molecule which then trapped inside.they have huge surface area so could make great industrial catalysts

34
Q

Properties of metals (metallic bonding)

A
  • giant structure
  • very high melting and boiling points
  • insoluble in water
  • malleable as layers of atoms in a pure metal can slide over each other
  • conducts electricity when solid or liquid
35
Q

Metallic bonding and delocalised electrons

A

Electrons in the outer shell oh the metal atoms are delocalised. There are strong forces of electrostatic attraction between positive metal ions and the shared negative electrons. These forces of attraction hold the atoms together in a regular structure

36
Q

Non-metal properties

A

Brittle, dull, lower boiling points, generally don’t conduct electricity often have lower density

37
Q

What is the relative formula mass of a compound

A

The relative atomic masses of all the atoms in its formula added together

38
Q

What is the molecular formula

A

Tells us how many atoms of each element are present

39
Q

What is the empirical formula

A

The molecular formula simplified down to its simplest ratio

40
Q

How to work out empirical formula

A
  1. find mass of element
  2. find relative atomic mass of element
  3. divide mass by by relative atomic mass
  4. divide Borge by the smallest number of the previous number
  5. simplify
  6. fraction/ratio
41
Q

How to work out molecular formula

A

Start by finding relative formula mass of the empirical formula then divide the relative formula mass by the relative formula mass of the empirical formula.finally multiply everything in the empirical formula by the result

42
Q

What is a mole

A
  • Avogadro’s constant number of particles of that substance

- a mass of ‘relative particle mass’ g

43
Q

How to find the number of atoms

A

No. Moles x avogadro’s constant

(6.02 x 10 ^23)

44
Q

What is the equation for moles

A

Mass
————————
Moles x Mr or Ar

45
Q

What’s the formula for finding concentration

A

M
————
C x V

If volume is in cm^3 then divide it by 1000 to get into dm^3

46
Q

What’s the limiting reactant

A

A reaction stops when all of one of the reactants are used up any other reactants are said to be in excess. The reactants thats used up in a reaction is called the limiting reactant

47
Q

How to work out the balanced symbol equation for a reaction if you know the masses of the reactants and products

A 
M
R
D
D
S
F
48
Q

How to work out limiting reactants

A 
M
R
D
D
S
F
49
Q

Describe the structure of an atom

A

Nucleus in centre contains protons and neutrons, surrounded by electrons in shells

49
Q

Explain how the existence of isotopes results in relative atomic masses of some elements not being whole numbers

A

If element has more than 1 isotope, it’s Ar is average of mass numbers of all different isotopes, taking into account how much there is of each one. So might not be whole number.

49
Q

Mendeleev thought he had arranged elements in order of increasing relative atomic mass why was this wrong?

A

Not always true because of relative abundance of isotopes of some pairs of elements in periodic table

49
Q

How are elements in periodic table ordered

A

Elements arranged in order of increasing atomic number , in rows (periods)and elements with similar properties placed in same vertical columns (groups)

49
Q

How are ionic bonds formed

A

When metal and non-metal react, metal atom loses electrons to form cation (positive ion) and non-metal gains these electrons to form anion (negative ion). These oppositely charged ions strongly attracted to one another by electrostatic forces. Attraction called ionic bond

50
Q

Explain the use of endings -ide and -ate in names of compounds

A

Ions with names ending in -ate are anions containing oxygen and at least one other element. Ions with names ending in -ide are anions containing only one element (apart from hydroxide ions)

51
Q

Explain the law of conservation of mass applied to a closed system including a precipitation reactions in closed flask

A

Total mass of system before and after doesn’t change (no stone crates or destroyed)
Eg. Copper sulfate solution reacts with sodium hydroxide to form insoluble copper hydroxide and soluble sodium sulfate

51
Q

Explain law of conservation of mass applied to a non-enclosed system including a reaction in an open flask that takes in or gives out a gas

A

In unsealed reaction vessel observe change of mass.
Mass increases:
Metal unsealed container reacts with oxygen from air, mass inside container increases
Mass decreases:
Metal carbonate thermally decomposed in unsealed container to form metal oxide and carbon dioxide gas , mass of container decrease as co2 escapes

Chemistry-Zoe Brown (10 decks)

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