Chapter 1.1 - Chemical bonding
How do elements form compounds? When the atoms of two or more elemts react they make a compound.
How do the elements in Group 1 bond with the elements in Group 7? Atoms of group 1 elements can lose one electron to gain the stable electronic structure of a noble gas. This electron can then be given to an atom from group 7, which then achieves the stable electronic structure of a noble gas.
Losing electrons to form positive ions: In ionic bonding the atoms have to lose or gain electrons to become charge particles called ions. The ions have the electronic structure of a noble gas.
Sharing electrons is called covalent bonding.
Transferring electrons is called ionic bonding.
An ion is a charged particle, that has the electronic structure of a noble gas.
Chapter 1.2 - Ionic bonding
How are ionic compounds held together? They are held together by very strong forces of attraction between the oppositely charged ions. OPPOSITES ATTRACT. This is called ionic bonding.
Which elements, other than those in groups 1 and 7, form ions? Elements in groups 2 and 6 also form ions, for example, magnesium reacts with oxygen, to form magnesium oxide. This is made up of magnesium ions with a double positive charge, and oxide ions with a double negative charge.
The ionic bonds between the charged particles result in an arrangement of ions that we call a giant structure or giant lattice.
Giant structure is a huge 3-D network of ions or atoms.
Chapter 1.3 - Formulae of ionic compounds
How can we write the formula of an ionic compound, given its ions?
Groups of metals:
The atoms of Group 1 elements form 1+ ions, e.g. Li+
The atoms of Group 2 elements form 2+ ions, e.g. Ca2+
Groups of non metals:
The atoms of Group 7 elements form 1- ions e.g. F-
The atoms of Group 6 elements form 2- ions e.g. S2-
The charges on the ions in an ionic compound always cancel each other out.
The formula of an ionic compound shows the ratio of ions present in the compound.
Sometimes we need brackets to show the ratio of ions in a compound, e.g. magnesium hydroxide, Mg(OH)2
When naming compounds we use -ide ending for simple non-metal ions such as sulfide, but we use -ate for ions that include oxygen, such as sulfate and nitrate.
Chapter 1.4 - Covalent bonding
How are covalent bonds formed? They are formed by non-metals reacting together their atoms share pairs of electrons to form molecules, which is known as covalent bonding.
What types of substance have covalent bonds? Substances with simple molecules, such as water and methane.
Covalent bonds are formed when atoms share pairs of electrons.
Giant covalent structures- Most are very small structures with simple molecules such as water, but some are very different, for example diamond. These are sometimes referred to as macromolecules, as huge numbers of atoms are held together by a network of covalent bonds.
The structure of a susgbatance held together by a network of covalent bonds is called a giant covalent structure.
Chapter 1.5 - Metals
How are the atoms in a metal arranged? They are built up layer upon layer in a regular pattern, which means they form crystals, which are not always obvious to the naked eye.
How are the atoms in metals held together? They are closely packed together and arranged in regular layers.
Metallic bonding is positively charged metal ions which are held together by electrons from the outermost shell of each metal atom . These are free to move throughout the giant metal lattice.