Atomic Structure and the Periodic Table - essential knowledge questions

State the masses of the subatomic particles.

Protons and neutrons have a relative mass of 1, electrons have a mass which is negligible.

What does the atomic number indicate?

The number of protons.

What does the mass number indicate?

The number of protons and neutrons.

What is the overall charge of an atom?

Atoms have no overall charge, due to equal number of protons and electrons.

What is the radius of an atom?

0.1nm

What is the radius of the nucleus?

1 × 10(power of -14)

How are electrons organised in their shells?

The first shell can hold a maximum of 2 electrons, all other shells can have a maximum of 8 electrons.

Who discovered the electron?

JJ Thomson.

What was the “plum pudding” model?

JJ Thomson came up with this; it suggests that the atom is a ball of positive charge with negative electrons embedded in it.

Who discovered the proton?

Rutherford.

What were the results from the alpha particle scattering experiment?

Rutherford fired positively charged alpha particles at gold foil. Some alpha particles were deflected because the nucleus of the atom, is positively charged. Most particles were not deflected because the atom is mainly empty space.

How did Neil Bohr adapt the nuclear model?

Bohr suggested that electrons orbit the nucleus at specific distances.

Who discovered the neutron?

James Chadwick proved that the nucleus contained neutrons as well as protons.

What is an isotope?

Isotopes of the same type of atom have the same number of protons and electrons, but have a different number of neutrons.

In the modern periodic table, how are the elements arranged?

In order of atomic number.

What does the group number tell you about an atom?

The number of electrons on the outer shell. Eg group 1 elements have 1 electron on their outer shell.

What are the group 1 elements also known as?

The alkali metals.

What are the group 7 elements also known as?

The halogens.

What are the group 0 elements also known as?

The noble gases.

How did elements used to ne organised in the early periodic table?

In order of their atomic weights.

Explain the pattern in reactivity as you go down group 7.

Decreases because the atoms get larger going down the group. This means that the outer shell gets further away from the nucleus and is shielded by more electron shells. The further the outer shell is from the positive attraction of the nucleus, the harder it is to attract another electron to complete the outer shell.

Why do halogens often pair up together to form diatomic molecules?

Halogens have 7 electrons on their outer shell, they need one more electron to have a full outer shell. Because of this, each atom pairs with another atom and shares an electron (covalent bond), forming a diatomic molecule.

What happens when halogens react with a different element?

They gain an electron into their outer shell and become negative ions. When this happens, they are called halides.

Name the physical properties of halogens.

Non metals and do not conduct electricity. They are brittle and crumbly as solids. They are poisonous and smelly. As you move down the group, they become darker in colour.

At room temperature, what colour and state are fluorine, chlorine, bromine and iodine?

Fluorine is a yellow gas. Chlorine is a green gas. Bromine is a red-brown liquid. Iodine is a grey solid.

In solution, what colour is chlorine, bromine and iodine?

Chlorine is pale green, bromine is orange, iodine is dark brown.

What would happen in this reaction : fluorine + sodium chloride → sodium fluoride + chlorine?

Fluorine is the more reactive halogen, so will displace chlorine from the sodium chloride compound. The yellow colour of chlorine would be seen as it is a product.

Where are transition metals found in the periodic table?

In the middle section.

Describe the properties of transition metals.

Good conductors of heat and electricity, dense, shiny and strong.

Compare the reactivity of transition metals with group 1 elements.

Transition metals are less reactive than group 1 and do not react as vigorously with water, oxygen or group 7 elements.

Compare the density and hardness of transition metals with group 1 elements.

Transition metals are denser, stronger and harder than group 1 metals.

Compare the melting point of transition metals with group 1 elements.

Transition metals have higher melting points.

What ions do transition metals form?

Most transition metals can form ions with different charged ions.

What do transition metal compounds normally look like?

They form different coloured compounds.

Give a use of transition metals in industry.

Transition metals and their compounds make good catalysts.

How did Mendeleev change the early periodic table?

Mendeleev left gaps for elements that he thought had not been discovered and in some places, changed the order based on their chemical properties instead of atomic weight.

What is an ion?

When an atom loses or gains an electron, it becomes positively or negatively charged. It is now an ion.

What ions do metals form?

They lose electrons, forming positive ions.

What ions do non metals form?

They gai electrons, forming negative ions.

Name 4 physical properties of metals.

They conduct thermal energy and electricity, they are shiny, malleable and have a high melting point.

Where are non metals found on the periodic table?

Towards the top right.

In group 7 and group 0, describe the pattern in melting point as you go down the group.

As you go down group 7 and 0, the melting point increases.

Explain the pattern in melting point as you go down group 7 and 0.

Increases because the atoms get bigger in size, so there are more intermolecular forces of attraction and more energy is needed to overcome the forces.

Describe the pattern in melting point as you go down group 1.

As you go down group 1, the melting point decreases.

Why are atoms in group 0 stable?

They have a full outer shell and are therefore completely inert (unreactive).

Describe the pattern in reactivity as you go down group 1.

As you go down group 1, the reactivity increases.

Explain the pattern in reactive as you go down group 1.

Increases because the atoms get bigger and have more shells. This means the outer electron is further from he nucleus and is more shielded. There is a weaker attraction between the nucleus and outer electron, so the outer electron is more easily lost.

What is the general equation for alkali metals reacting with water?

Alkali metal + water → alkali metal hydroxide + hydrogen.

What is observed when lithium reacts with water?

Lithium doesn’t melt, fizzing can be seen.

What is observed when sodium reacts with water?

Large amounts of heat are released causing sodium to melt. Hydrogen released catches fire and causes the ball of sodium to dash across the surface.

What is observed when potassium reacts with water?

Potassium melts into a shiny ball that dashes across the surface and hydrogen burns with a lilac coloured flame.

What happens when alkali metals react with oxygen?

They form metal oxides, producing a layer of dull oxide on the surface of the metal.

How is the reaction between alkali metals and oxygen prevented?

They are stored in oil to prevent them from reacting with oxygen in the air.

What happens when alkali metals react with chlorine?

They from chlorides which are all white crystalline solids that are soluble in water. E.g sodium + Charline → sodium chloride.

Describe the pattern in reactivity as you go down group 7.

As you go down group 7, reactivity decreases.

What is an atom?

An atom is the smallest part of an element that can exist.

What is an element?

Elements are made from one type of atom.

What is a compound?

Compounds are made from two or more elements which are chemically bonded.

How do you name a compound with 2 elements?

The first name is the metal element and the surname is the non metal.

How do you name a compound with 3 elements, one of which is oxygen?

The ending is -ate. E.g sodium carbonate.

What is the conservation of mass?

In a chemical reaction, no atoms are made or destroyed, so the mass of reactants = mass of products.

What is a mixture?

A mixture consists of two or more elements or compounds not chemically bonded together.

How could you separate an insoluble solid from a mixture?

By filtration.

How could you separate a soluble solid from a mixture?

Crystallisation.

What do the following state symbols mean : (g), (l), (s), (aq)?

Solid, liquid, gas, aqueous/ formed a solution.

What is distillation used to separate?

Two or more liquids with different boiling points.

Name the two changes of state in distillation.

The liquid evaporates when heated, the gas is then cooled and condenses back into a liquid.

Describe the method to separate two liquids by distillation.

• Heat the mixture in a round bottom flask.

• The liquid with the lowest boiling point will boil first.

• This liquid will evaporate and turn into a gas and enter the condenser.

• In the condenser, the gas will cool and then condense.

• The liquid is collected in the beaker and the other liquid will be left in the flask.

What is chromatography used to separate?

Chromatography is used to separate mixtures of more than one soluble substance dissolved in solution.

Why is the start line drawn in pencil?

Because pencil is insoluble and will not run.

Why must the solvent be below the start line?

So that the mixture does not dissolve into the solvent but instead is carried up the paper.

Name the three subatomic particles.

Electrons, protons and neutrons.

What is found in the nucleus of the atom?

Protons and neutrons.

Where are the electrons found?

They orbit the nucleus in electron shells.

State the charges of the subatomic particles.

Protons: +1, electrons: -1, neutrons: no charge.