Simple Model of the Atom (AQA GCSE Chemistry)

The elements present in calcium sulfate are calcium, sulfur and oxygen.

True.

Names of compounds which end in ‘-ite’ will always have less oxygen than ‘-ate’.

The formula of the following compound is C₃H₈.

The name of NH₃ is ammonia.

False.

Compounds can not be separated into elements by a physical process, only by a chemical reaction.

The name of C₂H₅OH is ethanol.

The name of CH₄ is methane.

The name of H₂SO₄ is sulfuric acid / hydrogen sulfate.

The name of HNO₃ is nitric acid / hydrogen nitrate.

The name of HCl is hydrochloric acid / hydrogen chloride.

The name of H₂O is water.

The name of SO₃ is sulfur trioxide.

Products are the new substances which are on the right-hand side of the arrow in a chemical equation, formed by the reaction of reactants.

The word equation for the reaction of silicon with oxygen to form silicon dioxide is:

silicon + oxygen silicon dioxide

Reactants are the substances on the left-hand side of the arrow in a chemical equation that react with each other to form new substances / products.

The (s) in a symbol equation indicates that the substance is solid.

The (l) in a symbol equation indicates that the substance is liquid.

The (g) in a symbol equation indicates that the substance is gas.

The (aq) in a symbol equation indicates that the substance is in solution / aqueous.

False.

The balanced symbol equation for the reaction of sodium with chlorine is:

2Na + Cl₂ 2NaCl

The word equation for the combustion of sulfur to produce sulfur dioxide is:

sulfur + oxygen → sulfur dioxide

The missing numbers to balance the equation are:

N₂ + 3H₂ ⇌ 2NH₃

The symbol equation for the reaction of magnesium with chlorine to form magnesium chloride is:

Mg + Cl₂ MgCl₂

A half equation is a representation of what happens to the electrons in reactions where atoms, molecules or ions are gaining or losing electrons.

2Br^- + Cl₂ Br₂ + 2Cl^- is an ionic equation.

2KI + Br₂ 2KBr + I₂ is not an ionic equation because there are no ions.

The completed half equation is Pb²⁺ + 2e^- → Pb

The completed half equation is: 2Cl^- → Cl₂ + 2e^-

The ionic equation for the following reaction is:

H⁺ + OH^- → H₂O

Spectator ions are ions which appear on both sides of an ionic equation and are eliminated from the final equation.

Simple distillation is used to separate:

• a liquid and soluble solid from a solution (e.g., water from a solution of salt water)

• a pure liquid from a mixture of liquids.

Simple distillation is a technique used to separate a liquid from a solution (e.g., water from a salt solution) by boiling the solution and condensing the vapour.

Fractional distillation is a technique used to separate two or more liquids that have different boiling points from a mixture.

Filtration separates an undissolved solid from a mixture of solid and liquid.

Crystallisation is used to separate a dissolved solid from a solution.

It is important that the solid (solute) is much more soluble in hot solvent than in cold.

Paper chromatography depends upon the solubility of different substances.

Paper chromatography is used to separate substances that have different solubilities in a given solvent, such as identifying the components of a mixture.

The mobile phase in chromatography is the solvent / liquid that travels up the paper.

The baseline (starting line) should be drawn in pencil because it will not contaminate the results / will not run.

False.

In paper chromatography, a pure substance only produces one spot.

The technique that separates solutions with more than one type of dissolved solid is chromatography.

A mixture is a combination of two or more substances that are not chemically joined together

Physical processes are used to separate mixtures.

Rutherford's scattering experiment revealed that most of an atom's mass is concentrated in a region of space at the centre of the atom called the nucleus.

Niels Bohr proposed that electrons orbit the nucleus in fixed shells.

The diagram represents the plum pudding model.

The model is the Bohr model of the atom.

James Chadwick provided the evidence to show the existence of neutrons within the nucleus.

During Rutherford's experiment some particles were scattered and a few were deflected directly back.

The plum pudding model suggested that the atom is a ball of positive charge with negative electrons embedded in it.

The three subatomic particles that make up atoms are:

• Protons

• Neutrons

• Electrons.

A proton is a subatomic particle with a relative charge of +1 found in the nucleus of an atom.

The relative charge of a neutron is 0 (neutral).

True.

Atoms are always neutral overall because the number of protons equals the number of electrons in a neutral atom.

The mass of an atom is concentrated in the positively charged nucleus.

Protons and neutrons are located in the nucleus of an atom?

Electrons are located in the shells / orbits around an atom.

The approximate radius of an atom is about 1 x 10^-10 metres or 0.1 nanometres.

The radius of the nucleus is about 10,000 times smaller than that of the atom.

True.

The atomic number determines the position of an element on the periodic table.

The number of protons, neutrons and electrons in an atom of are:

• Protons = 13

• Neutrons = 27 - 13 = 14

• Electrons = 13

The number of electrons in an atom is the same as the number of protons / the atomic number.

Atomic number tells us the number of protons in the nucleus of an atom.

An isotope is an atom of the same element containing the same number of protons but different numbers of neutrons.

The number of protons, neutrons and electrons in are:

• Protons = 1

• Neutrons = 3 - 1 = 2

• Electrons = 1

False.

Isotopes display the same chemical characteristics.

The chemical characteristics of an atom are determined by the number of electrons in the outer shell.

The mass number (or nucleon number) is the total number of protons and neutrons in the nucleus of an atom

Two pieces of information required to calculate the relative atomic mass of an element are:

• The mass numbers of each isotope.

• The (relative / percentage) abundances of each isotope.

The equation for calculating relative atomic mass in terms of the percentage abundance and mass of isotopes A and B is:

False.

The relative atomic mass of an element is calculated using the mass numbers and relative abundances of all its isotopes.

In terms of isotopes, abundance is the amount of each isotope present in a sample of an element.

The isotopes are and .

is not an isotope because it is a different element (nitrogen not carbon).

False.

Relative atomic mass is calculated by:

• Multiplying the abundance of each isotope by its mass

• Adding these numbers together

• Then, dividing this value by the total abundance.

Isotopes have the same symbol and same atomic numbers but different mass numbers.

After calculating the A_r, you would identify an element by looking for the value on the Periodic Table.

For example, A_r = 23. On the Periodic Table, the element with an A_r of 23 is sodium.

The relative atomic mass of the element is:

= 69.8 or 70

An electronic configuration is the arrangement of electrons in shells.

True.

Electrons occupy the shell closest to the nucleus first.

The first shell can hold a maximum of 2 electrons.

The group gives the number of outer electrons.

True.

Chlorine has 3 shells of electrons.

The last number in an electronic configuration represents the number of outer electrons.

The second and third shells can each hold a maximum of 8 electrons.

In terms of electrons, other words for shell include:

• Orbit

• Orbital

False.

Most elements do not have full outer shells of electrons.

The electronic configuration of sulfur is 2, 8, 6.