Slides in this set
Rocks and Building
What you need to know on this topic:
All Substances are made of atoms that have tiny central nucleus surrounded by electrons
The simplest substances contain only one type of atom and are called elements
Atoms of each element have their own chemical symbol
The periodic table lists all the known elements in groups with similar chemical properties
Elements form compounds by combining with other elements:their atoms give, take or share
electrons, so they bond together.
The formula of a substance shows the types of atom it contains and how many have combined
In chemical reactions, the mass of the reactants is always the same as the mass of the products
Chemical equations are balanced. There is the same number of each type of atom on each side
Limestone is used as a building material and to make quicklime, slaked lime, cement and glass
Heating metal carbonates produces metal oxides and carbon dioxide gas…read more
Atoms, Elements and Compounds
All substances are made up out of atoms.
Atoms are represented by a chemical symbol, e.g. Na for an atom of sodium, O for an
atom of oxygen.
The Nucleus is in the middle of the atom, it contains Protons and Neutrons. Electrons
move around the nucleus in shells. The total number of electrons in an atom is
always the same as the number of protons in the nucleus.
The number of protons in an atom is called its atomic number - also called the proton
number. Atoms are arranged in the periodic table in order of increasing atomic
Protons have a positive charge, Neutrons have no charge and Electrons have a
negative charge. Because the number of Electrons and Protons are the same atoms
have no overall electrical charge.
Compounds are when two or more elements are chemically bonded together. This
usually involves giving or sharing electrons…read more
Electrons are arranged in different shells around the nucleus. The innermost shell is
filled first. Each succeeding shell can only hold a certain number of electrons before it
becomes full. The innermost shell can hold a maximum of two electrons, the second
shell a maximum of eight, and so on.
A vertical column of elements in the periodic table is a group. The elements in a group
have similar chemical properties to each other.
At Gcse level we need to know the first 20 elements and their atomic structure…read more
Compounds formed from metals and non-metals consist of ions. Ions are charged
particles that form when atoms lose or gain electrons: metal atoms lose electrons to
form positively charged ions. Non-metal atoms gain electrons to form negatively
charged ions. The ionic bond is the force of attraction between the oppositely charged
Compounds formed from non-metals consist of molecules. The atoms in a molecule are
joined together by covalent bonds. These bonds form when atoms share pairs of
Balancing an equation means there must be the same number of atoms on both sides.
We can do this by putting numbers in front of formulas when needed.
An example of an unbalanced equation: Cu + O2 CuO
A balanced equation: 2Cu + O2 2CuO…read more