C1 : Atomic Structure and the Periodic Table

What does an atom contain? (3)

• Protons

• Neutrons

• Electrons

What is a radius of an atom?

1×10^-10 m

Where is the nucleus located, what does it contain, what is its radius, what is its overall charge?

• Located in the centre of the atom

• It contains protons + neutrons

• Its radius is 1 × 10^-14 m

• Its overall charge is positive because of the protons

Where are the electrons located in an atom?

In the shells which orbit the nucleus

What is the mass and charge of the 3 subatomic particles?

• Protons

  • Mass → 1

  • Charge → +1

• Neutrons

  • Mass → 1

  • Charge → 0

• Electrons

  • Mass → Very small

  • Charge → -1

What is the overall charge of atoms + why?

• Neutral

• Because they have the same number of protons and electrons which balance each other out

What is an ion + what overall charge would an atom have if lost or gained?

An atom with an unbalanced number of electrons

• Lost electrons → + charge

• Gained electrons → - charge

What are atoms represented by?

A chemical symbol

What is a molecule?

two or more elements chemically bonded together

What is an element?

One type of atom only

What is an isotope?

Element with a different number of neutrons

What is the equation for relative atomic mass?

What is a compound?

Substances made up of 2 or more elements chemically joined together

During a chemical reaction what is a formed?

At least one new substance

Do compounds have the exact same properties as their original elements?

No

What are compounds represented by + give an example?

Formulas e.g. CO2

What are the 2 ways a chemical equation can be written?

• Word equation

• Symbol equation

What does the purple + the green represent?

• Purple → Reactants

• Green → Products

Balance this equation

What is a mixture?

Different elements or compounds not chemically joined together

What does it mean if a substance is soluble?

It can dissolve in a liquid

What does mean if a substance is insoluble?

It can’t be dissolved in a liquid

What are the 4 physical separation techniques?

• Chromatography

• Filtration

• Crystallisation

• Distillation

What is chromatography used to separate?

inks and dyes

Explain how to do chromatography (7)

1. Draw a line near the bottom of a sheet of filter paper, use a pencil (pencil is insoluble and won’t dissolve in the solvent)

2. Add a spot of ink to the pencil line and place the sheet in a beaker of solvent e.g. water or ethanol

3. Make sure the ink isn’t touching the solvent

4. The solvent should seep up the paper carrying the ink with it

5. Each different dye will move up the paper at different rates so the dyes will separate out, each dye will form a spot in a different place

6. If any of the dyes are insoluble then they will stay on thee baseline

7. Leave the paper to dry after the dyes have separated

What is separated using filtration?

Insoluble solid from liquids

Explain how to do filtration (4)

1. Get filter paper and fold it into a cone

2. Put the cone into a filter funnel

3. Put that into a beaker

4. Put the mixture in the funnel + wait till all the solids are in the paper and the liquid is in the beaker

What is evaporation used to separate?

Soluble salt from a solution (don’t do thermal decomposition)

Explain how to do evaporation (4)

1. Pour the solution into an evaporating dish

2. Slowly heat the solution, the solvent will evaporate and the solution will get more concentrated

3. Crystals will start to form

4. Keep heating the evaporating dish until all you have left is dry crystals

What is crystallisation used to separate?

Soluble salts from a solution

Explain how you would do crystallisation (5)

1. Pour the solution into an evaporating dish and gently heat the solution

2. The solvent will evaporate and the solution will get more concentrated

3. Once the some of the solvent has evaporated or when you see crystals start to form, remove the dish from the heat and leave the solution to cool

4. The salt should start to form crystals as it become insoluble in the cold, a highly concentrated solution

5. Filter the crystals out of the solution and leave them in a warm place to dry

What are the 2 types of distillation?

• Simple distillation

• Fractional distillation

What is simple distillation used to separate?

2 substances with very different boiling points

Explain how to do simple distillation (3)

1. Heat the solution, the part of the solution that has the lowest boiling point will evaporate first

2. The vapour is then cooled, condenses and is collected

3. The rest of the solution is left behind in the flask

What is fractional distillation used to separate?

A mixture of liquids with different boiling points

Explain how to do fractional distillation (6)

1. Put the mixture in a flask and put a fractionating column on top

2. Then start to heat the mixture

3. The different liquids will have different boiling points so they will evaporate at different temperatures

4. The liquid with the lowest boiling point evaporated first, it will reach the top of the column

5. Liquids with higher boiling points might also start to evaporate but the column cooler at the top so it will condense

6. When the first liquid has been collected raise the temperature until the next one reaches the top and so on and so forth

Explain the history of the atom (give the date, the person and the discovery) (5)

• 19th century ~ John Dalton → atoms are solid spheres

• 1879 ~ J J Thompson → plum pudding model

• 1909 ~ Earnest Rutherford → alpha scattering experiment + nuclear model

• Niels Bohr → electrons orbit the nucleus in fixed shells, each shell being a fixed distance

• James Chadwick → neutrons

Describe the plum pudding model

A ball of positive charge with negative electrons embedded into it

Describe the alpha particle scattering experiment (3)

• Positively charged alpha particles were thrown at an extremely thin sheet of gold

• From the plum pudding model the particles were expected to pass straight through the sheet of gold or be only slightly deflected

• However even though most of them did go through, more were deflected than expected and some came right back

What did the alpha particle scattering experiment conclude? (3)

• That the mass of an atom was concentrated at the centre (nucleus)

• The nucleus was charged

• The atom was mostly empty space

Describe the nuclear model (2)

• A tiny positively charged nucleus at the centre in which most of the mass is concentrated

• A cloud of negative electrons surround this nucleus

Why did Niels Bohr suggest that electrons orbited the nucleus?

Because the electrons would be attracted the the nucleus and the atom would collapse

How many electrons are allowed on the first shell?

2

How many electrons are allowed on the 2 + the rest of the shells?

8

Draw the electronic structure of sodium

Write the electronic configuration of sodium

2,8,1

What 3 ways were elements arranged in the early 1800s?

• Physical properties

• Chemical properties

• Atomic weight

Who made the table of elements, when did he make + how did he arrange it?

1869 ~ Dimitri Mendeleev → He left gaps for elements that hadn’t been discovered + he ordered it atomic weight

How is the modern periodic table arranged?

In order of increasing atomic number

Where letter represents metals?

A,B,C

Where letter represents non-metals?

D

What do the periods on the periodic table tell you?

Number of shells

What do the groups on the periodic table tell you?

Number of electrons on the outer shell

How do elements in each group behave?

Similarly

What type of elements form positive ions + which ones don’t?

Metals form positive ions + non-metals don’t

Why do atoms react?

To form a full outer shell

What are the properties of metals? (7)(sscchhm)

• Strong

• Malleable

• Conduct heat

• Conduct electricity

• High melting points

• High boiling points

• Shiny

What are the properties of non-metals? (5)

• Dull

• Brittle

• Aren’t solid at room temperature (some of them)

• Don’t conduct electricity

• Low density

Which letter represents the transition metals?

B

What are the properties of transition metals? (15)

• Less reactive than group 1 + 2 (more useful)

• Hard

  Ductile

• Sonorous

• Used as catalyst

• Forms ions with multiple charges

• High densities

• Form coloured compounds

• Shiny (lustrous)

• Malleable

• Strong

• Conducts heat

• Conducts electricity

• High melting points

• High boiling points

When are transition metals used as catalysts? (2)

• Iron catalyst used in the Haber process for making ammonia

• Nickel catalyst used in making margarine

What are group 1 elements called?

Alkali metals

How many electrons in their outer shells do group 1 elements have?

1

What are the properties of alkali metals? (4)

• Soft

• Low density

• Form 1+ ions

• Form ionic compounds

What is the trend of the alkali metals as you go down the group? (2)

• More reactive

• Melting + boiling points decrease

Why are the group 1 elements more reactive when you go down the group?

The outer electron is lost more easily as the attraction between the electron and the nucleus decreases because the electron is further away from the nucleus

How do group 1 elements react with water + what do they produce?

• They react vigorously

• They produce hydrogen gas + metal hydroxides (compounds that dissolve in water to produce alkaline solutions)

How do group 1 elements react with chlorine + what do they form?

• They react vigorously

• They form white metal chloride salts

How do group 1 elements react with oxygen + what do they form?

• They react vigorously

• They from a metal oxide

What are the differences between alkali metals and transition metals in terms of their chemical properties and physical? (7)

	Chemical Properties	Physical Properties
Alkali Metals	Very reactive with water, halogens + oxygen Not used as a catalyst White colourless compounds Only form 1+ ions	Low melting points Low densities Soft
Transition Metals	Lowly reactive with water, halogens + oxygen Used as a catalyst Coloured compounds Ions form multiple charges	High melting points High densities Strong + hard

What are the group 7 elements called?

Halogens

How many electrons on their outer shells do group 7 elements have?

7

How do group 7 elements exist?

As diatomic molecules

What are the properties of halogens? (2)

• Form 1- ions when reacting with metals called halides

• More reactive halogens can replace a less reactive halogen (displacement reaction)

What is the trend of the group 7 elements going down the group? (2)

• Less reactive

• Melting + boiling points increase

Why do group 7 elements become less reactive when going down the group?

Its harder to gain an extra electron, because the outer shell is further away from the nucleus

What are the group 0 elements called?

Noble gases

How many electrons do group 0 elements have in their outer shells?

8 + helium has 2 (all have a full outer shell)

What are the properties of noble gases? (3)

• Inert → don’t react with anything

• Exist as monotonic gases → single atoms

• Non-flammable

What is the trend of the noble gases as you go down the group?

Increased boiling points (more intermolecular forces to overcome)