chemical changes and structure

What do elements in the same group of the periodic table have?

The same number of electrons in their outer shell which means they have similar chemical proper

What is the electron arrangement for the first 20 elements?

What does the nucleus of an atom contain?

The subatomic particles protons and neutrons

What are electrons?

Subatomic particles that orbit the nucleus of an atom

What are the mass of electrons, protons and neutrons?

Protons and neutrons have an approximate mass of 1 atomic mass unit- a.m.u and that electrons in comparison have virtually no mass

How are elements arranged in the periodic table?

In order of increasing atomic number.

What is the atomic number?

The atomic number gives the number of protons in an atom.

What does a neutral atom consist of?

Equal number of protons and electrons

Mass number of an atom is?

The number of protons and neutrons added together

What are isotopes?

Atoms of the same element with the same atomic number but different mass numbers

Isotopes have

The same number of protons and electrons but different numbers of neutrons

What is nuclide notation and can you write it?

Shows the atomic number, mass number ( and charge) of atoms ( ions)

What does nuclide notation tell us?

Tells us the number of protons, neutrons, and electrons in an atom or ion

What do most elements have

2 or more isotopes

What is relative atomic mass?

Is the average mass of all the isotopes in a sample, taking into account the proportion of each isotope.

How do you calculate the relative atomic mass and can you?

Using the mass and proportion of each isotope present

What are covalent bonds

They form between non- metal atoms.

How is a covalent bond formed?

When 2 positive nuclei are held together by their common attraction for a shared pair of electrons.

Can you draw an electron cloud diagram and what is it?

Shows how outer electrons are shared to form the covalent bond(s) in a molecule

What are the 7 elements that exist as diatomic molecules though the formation of covalent bonds

Br2, I2, N2, Cl2, H2,O2, F2

What does the shape of simple covalent molecules depend on?

The number of bonds and the orientation of these bonds around the central atom.

Describe the shape of simple covalent molecules

Linear, angular, trigonal pyramidal and tetrahedral.

How many bonds can be formed between atoms?

More than one bond can be formed between atoms, leading to double or triple covalent bonds

When are ions formed?

When atoms lose or gain electrons to obtain the stable electron arrangement of a noble gas.

What do metal atoms do to form positive ions

They lose electrons

What do metal atoms do to form negative ions

Gain electrons

What are ionic bonds?

The electrostatic attraction between positive and negative

What do ionic compounds form

Lattice structures of oppositely charged ions with each positive ion surrounded by negative ions and each negative ion surrounded by positive ions.

What is the conduction in ionic compounds

The movement of ions towards oppositely charged electrodes.

What are ionic bonds?

Electrostatic attractions between positive and negative ions.

Electricity for ionic compounds

Do not conduct electricity when solid, but conduct electricity when molten or in a solution.

When and why do ionic compounds conduct electricity

Only when molten or in solution as the ionic lattice structure breaks up allowing the ions to be free to move.

Ionic compounds melting and boiling points

Ionic compounds have high melting points and boiling points because strong ionic bonds must be broken in order to break up the lattice.

Ionic compounds solubility

Ionic compounds are soluble in water

What happens when an ionic compound dissolves in water?

The lattice structure breaks up and the separated ions become surrounded by water molecules.

What can covalent substances form?

Either discrete molecular structures or giant network structures

Covalent molecular substances and there bonds..

Covalent molecular substances have strong covalent bonds within the molecules and only weak forces of attractions between molecules.

Covalent molecular substances melting and boiling points

They have low melting points and boiling points as only weak forces of attraction between molecules are broken when a substances changes state.

Why do covalent molecular structures not conduct electricity?

As they do not have charged particles ( ions/ electrons) which are free to move.

What is a covalent network structures like?

One giant structure composed of strong covalent bonds.

Melting and boiling points of covalent network structures?

Covalent network structures have very high melting and boiling points as much energy is needed to break many strong covalent bonds

Do covalent network structures dissolve in water?

No

Where do compounds get there names from

The names are derived from the name of the elements from which they are formed

How many elements are in compounds that end in ide?

2

What do compounds that end in ite or ate contain as elements

Oxygen

How to write chemical formula for 2 element compounds?

Using valency rules and a periodic table

What figures do you use to indicate the valency of an element

Román numerals

What is valency

The number of unpaired electrons

What does the formula of a covalent moleculer substance give us?

The number of each type of atom present in a molecule

What does the formula of a covalent network give us

The simplest ratio of each type of atom in the substance

What are ions containing more than 1 type of atom referred to as?

A group of ions

What does ionic formulae give us?

The simplest ratio of each type of ion in the substance.

When writing the chemical formula for ionic compounds what does it show?

The charges on each ion

In chemical formula what must the charges be?

Superscript

What do the numbers of atoms/ ions have to be in chemical formula?

Subscript