C1 Atomic Structure and the Periodic Table

What are all substances made up of?

atoms

What is the smallest part of an element that can exist?

An atom

How are compounds represented?

By a chemical formula

What do scientists use a chemical forumla for? [2]

- The different elements in a compound - How many atoms of each element one molecule of the compound contains

How can compounds be separated into their component elements? [2]

- Chemical reactions - Electrolysis

What side is the reactants on?

Left-hand side

What side are the products on?

Right-hand side

What is the total mass of the products of a chemical reaction always equal to?

To the toal mass of the reactants. This is because no atoms are lost or made

What charge are protons?

Positive charged

What charge are neutrons?

Neutral

What charge are electrons?

Negative charge

What are compounds?

A compound contains atoms or two or more elements, which are chemically combined in fixed proportions.

What is mixture?

A mixture consists of two or more elements or compounds, which are not chemically combined. The components in a mixture still retain their properties.

How can mixtures be separated?

By physical processes.

What do you use filtration for?

Filtration is used to separate soluble solids from insoluble solids.

What is crytallisation used for?

Crystallisation is used to obtain a soluble solid from a solution.

What is simple distillation?

Simple distillation is used to obtain a solvent from a solution.

What is fractional distillation?

Fractional distillation is used to separate mixtures in which the components have different boiling points.

What is chromatography?

Chromatography is used to separate the different soluble, coloured components of a mixture.

In early models, what did people use to think atoms were?

They were thought to be tiny spheres that could not be divided into simpler particles.

Who discovered the electron in 1897?

J.J Thomson

What is an atom overall charge?

Neutral

What did Thomson thought atoms contained?

Tiny, negative electrons surrounded by a sea of positive charge. This was called the `plum-pudding` model.

What did Geiger and Marsden bombard with against a thin sheet of gold in their experiment?

Alpha particles

What happened to the alpha particles in the gold sheet eperiment? [2]

- Most of the positively charged alpha particles passed straight through the atoms - Tiny number was deflected back towards the source

What did Rutherford conclude when he looked at the results? [2]

- The positive charge in an atom must be concentrated in a very small area. - This area was named the 'nucleus' and the resulting model became known as the 'nuclear' model.

What did Bohr deduce from the electrons?

That the electrons must orbit the nuclus at specific distances, otherwise they would spiral inwards.

What is the number of protons in an atom called?

The atomic number.

What is the sum of the protons and neutrons in an atom called?

Mass number

How are the elements in a modern periodic table arranged?

In order of increasing atomic number.

How do you work out the number of neutrons in an element?

Number of neutrons = mass number - atomic number

What is an isotope?

Isotopes of an element have the same number of protons but a different number of neutrons.

What can atoms gain or lose to become ions? [3]

Atoms can gain or lose electrons to become ions: - Metal atoms lose electrons to form positive ions. - Non-metal atoms gain electrons to form negative ions.

What does the electron configuration of an atom show?

How the electrons are arranged around the nucleus in shells.

What do electrons in an atom occupy?

The lowest available shell or energy level.

What do the first 20 elements hold? [2]

- The first shell can only hold a maximum of two electrons - The next two shells can each hold a maximum of eight electrons

What did John Newland notice when putting together the periodic table?

He noticed periodicity (repeated patterns), although missing elements caused problems.

How did strictly following the order of atomic weight create issues?

It meant some of the elements were in the wrong place.

What did Dmitiri Mendeleev notice?

He realised that some elements had yet to be discovered. When he created his table, in 1869, he left gaps to allow for their discovery. He also reordered some elements.

What are the elements in Group 0 known as?

Noble gases

What did Noble Gas atoms have a full of?

A full outer shell of electrons.

What does a full outer shell of electrons mean for noble gases?

It means they have a very stable electron configuration, making them very unreactive non-metals.

What are the elements in Group 1 known as?

Alkali metals.

What makes alkali metals different to others? [3]

- Have one electron in their outermost shell - Have a low melting and boiling point that decrease down the group - Become more reactive down the group

Why are alkali metals so reactive?

Because their outer electron gets further away from the influence of the nucleus, so it can be lost more easily.

Why are Alkali metals stored under oil?

Because they react very vigorously with oxygen and water, including moisture in the air.

What happens when alkali metals react with water?

A metal hydroxide is formed and hydrogen gas is given off. Potassium + Water -------> Potassium Hydroxide + Hydrogen

What do group 1 metals have a low of?

Low density - lithium, sodium and potassium are less dense than water, so they float on top of it.

What happens when a metal hydroxide is dissolved in water?

An alkaline solution is produced.

What is formed when Alkali metals react with non-metals?

An ionic compound.

What are the group 7 elements and what are they known for?

Group 7 elements are non-metals and are known as halogens. They have seven electrons in their outermost shell.

Why does the reactivity decrease in the Group 7 elements? [2]

- Outer shells are further from the electrostatic attraction of the nucleus, so its harder for them to gain an electron - More shielding causes electrons to repel

What is formed when Halogens react with metals?

Ionic salts

What will a reactive halogen do to a less reactive halogen?

The more reactive halogen will displace a less reactive halogen from an aqueous solution of it's salt. For example: - Chlorine will displace bromine from potassium bromide and iodine from potassium iodide - Bromine will displace iodine from potassium iodide.

What is the relative atomic mass?

Relative atomic mass is the average mass of the atoms of an element compared to one-twelfth of the mass of a carbon-12 atom.

How do you work out the relative atomic mass?

What is a molecule?

A group of two or more atoms joined together by covalent bonds.

When an alkali metal reacts with non-metals, it forms an ionic compound. What happens to the metal atom?

When this happens the metal atom loses one electron to form a metal ion with a positive charge.

When a halogen reacts with a metal to form an ionic salt, what happens to the halogen atom?

It gains 1 electron to form a halide ion with negative charge

What is the radius of an atom?

1x10-10m

What is the radius of a nucleus?

1x10-14m