TOPIC 1 FUNDAMENTAL IDEAS
1.1 Atoms and Elements
An atom is the smallest part of an element that can exist.
An Element is a substance cointaining atoms which all have the same number of protons
Elements are also the simplest substance as they cannot be broken down anymore, elements can only be changed into other elements
All substances are made up of atoms.
Elements contain only one type of atom
Compounds contain more than one type of atom chemically bonded together
An atom has a tiny nucleus in its centre and it is surrounded by electrons in a shell.
In a outer shell their can only be upto 8 electrons and in the inner shell their can only be two electrons.
1.2 Atomic Structure
Atoms are made up of protons, neutrons and electrons.
Atomic number = number of protons which is the same as the number of electrons.
Mass Number = number of protons + number of neutrons
1.3 Arrangement of electrons in atoms
The electrons in an atom are arranged in levels of shells
Atoms with the same number of electrons in the outermost shell belong in the same group of the periodic table
the number of electrons in the outermost shell of an element's atom determines that element reacts
First shell holds 2 electrons Second shell holds up to 8 electrons
Once the second shell has 8 electrons the third shell can also hold up to 8 electrons
1.4 Forming Bonds
Metal atoms form positively charged ions
NON-Metal Atoms form negatively charged ions
These oppositely charged ions attract each other in ionic bonding
When metals react with non-metals, charged particles called ions are formed
Atoms from different elements react together to form compounds. The formula of a compound shows the number and type of atoms that have bonded
Atoms of non metals bond to each other by sharing electrons. This is called COVALENT BONDING.
Balancing equations: 2Mg + 02 - 2MgO
Atoms can't be created or destroyed in a chemical reaction: total mass of reactants = total mass of products