Chemistry
Octet Rule
8 electrons in Valence Shell
Fulfilling Octet Rule
Gaining Electrons
Losing Electrons
Duet rule
H,B,Be Tend to combine to have 2 electrons in outer shell
The first electron shell can only hold 2 electrons
Electronegativity
Attracts shared pair of electrons
Periodic trends
Increases across period
Atomic Size decreases
Bonding
To fulfill the octet rule , there are ways an atom can gain or loose electrons
Metallic Bonding
Ionic Bonding
Covalent Bonding
Bonding b/w 2 non metals
have small or no diff in the electronegativity values
Non Metals have strong pull so they cannot remove electrons from another non metal to fulfil the octet rule. so they tend share electrons.
ex:
chlorine atoms need 1 electron to fulfil the octet rule, this can be achieved by 2 chlorine atoms by sharing an electron each
Properties
Usually liquids or gases
Cannot conduct electricity
Insoluble in water
Have low melting and boiling points
Exceptions
Hydrongen, Choride and Ammonia are soluble in water
Occurs b/w metals and non Metals
Atoms tend to have large difference in electronegative value
Non Metals have very strong pull and are capable of completely removing electrons from the metals
The metal ions are +vely charged and non metal ions are negative charged so they tend to attract to each other.
Properties
Usually crystalline solids
Have high melting and boiling points
Conduct electricity when molten or dissolved in water
Are soluble in water, and form aqueous solution
Lattice Structure of Ionic Bonding
Ionic compound is a giant structure of Ions
Have a regular repeating arrangement called Ionic lattice
Lattice is formed because the ion attracts each other and form a regular pattern with opposite charged ions next to each other.
Because atoms do not exist in isolation and instead form molecular compounds by combining with other atoms, the concept of electronegativity is important because it determines the nature of bonds between atoms.
It determines how the shared electrons are distributed between the two atoms in a bond. The more strongly an atom attracts the electrons in its bonds, the larger its electronegativity.
In ionic bonding there are two forces - metals which are cation and non-metals which are negatively charged ions. In ionic bonding the non-metals have a strong pull on electrons and are capable of withdrawing electrons totally from metals. This represents electronegativity as the atom let take chloride and sodium, the chloride atom is a non mental and pulls the electrons from the metal(Sodium). The pulling of electrons is known as electro negativity
have low volatility
The positive and negative ions are trapped in fixed locations and cannot move freely in the solid state. As a result, ionic substances in the solid form are unable to conduct electricity. When ionic substances are heated or dissolved in water, the positive and negative ions separate and become mobile, allowing them to move around freely.
In the solid and liquid phases, covalent compounds are made up of simple covalent molecules. In these two states, there are no free mobile ions. As a result, in the solid and liquid phases, covalent molecules are unable to conduct electricity.