Chemical Bonding

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Chemical Bonding by Mind Map: Chemical Bonding

1. Metallic Bonding

1.1. Structure

1.1.1. Atoms packed closely in an orderly manner .

1.1.2. Each atom loses valance electron [delocalised] to form cation Delocalised electrons forms a'sea of delocalised electrons' around metal cations electrons are smaller and lighter to MOVE ABOUT , while metal ions are too large and cannot move about .

1.2. Definition : electrostatic force of attraction between the positive metal ions and the 'sea of mobile delocalised electrons '

1.3. Physical properties of Metals

1.3.1. High Melting & boiling points - large amount of heat needed to overcome forces between the =ve cations and 'sea of delocalised electrons'

1.3.2. Malleable & Ductile - Ions are arranged in orderly layers which slide over one another when force is applied BUT do not REPEL due to the 'sea of delocalised electrons' that maintain neutrality .

1.3.3. Good conductor of electricity - 'sea of delocalised electrons' as charge carriers .

1.4. Conducts electricity at ALL STATES - due to mobile electrons

2. Ionic Bonding

2.1. Atoms forming Ions

2.1.1. Metal Ions : Lose electrons to form positively charged ions [Cations]

2.1.2. Non-metal Ions : Gain electrons to form negatively charged ions [Anions]

2.1.3. Define Ions : A charged particle formed from an atom or a group of atoms by the loss or gain of electrons & receives octet structure of a noble gas .

2.1.4. Notes : A [ ] and the charge of electron (+/-) must always be included when drawing an ion

2.2. Stable Noble Gas Configuration

2.2.1. Atoms of NOBLE GASES [Group O elements] are monatomic , unreactive [inert] & stable . They exist as individual atoms .They do not combine with other atoms to form compounds . Valance [outer] shells of noble gases : They have completely filled outer electron shells . An atom is stable if it has an octet structure [8 outer electrons] or a duplet structure [2 outer electrons]. This structure is known as noble gas structure .

2.2.2. All other atoms are unstable in the Periodic table as they do not have the noble gas structure , thus these atoms will try to achieve the stable duplet or octet structure by forming chemical bonds .

2.3. Formed between metal & non metals .

2.4. Forming Ionic Bonds

2.4.1. A metal loses electron(s) to a non-metal atom to achieve stable noble gas structure . Which forms ionic compounds : +ve & -ve arranged in a crystal lattice [Orderly arrangement of particles in 3 dimensions]

2.4.2. Ionic Bond : Strong electrostatic force of attraction that exists between positive and negative ions formed by a transfer of valance electrons form a metal to non-metal .

2.4.3. Notes : 'Dot and Cross' diagrams - unless the question says 'show ONLY the outer electrons' you need to draw ALL electrons and shells for the atom/ion

2.4.4. Questions regarding forming of ions , answering skills : 1. electronic configuration , 2. loss/gain/share, 3. charge of ion, 4. Formula of ion [3&4 for ionic compound only]

2.5. Properties of Ionic Compounds

2.5.1. Structure : Giant Ionic Lattice [Cations & anions are arranged alternate to each other ] - Each cation [depending on size and charge] is surrounded by 6 anions , hence ionic compounds are rigid .

2.5.2. Volatility : High melting & boiling points since large amounts of energy is required to overcome strong electrostatic forces of attractions between ions in lattice structure . Hence , they are SOLIDS at room temp. Ans skills on comparison of 2 ionic compounds : 1. charges , 2. which ion has bigger charge [stronger] , 3. energy needed to overcome force

2.5.3. Solubility : Soluble in water but not in organic solvents - as water has a partial charge which attracts opp charged ions to separate them from solid crystal lattice structure .

2.5.4. Electrical Conductivity ; Conducts electricity only in molten & 'solution' state when dissolved in water . - Ions are free to move to carry current .

3. Covalent Bonding

3.1. Simple Molecular Structure

3.1.1. Structure : Exist as small discrete molecule . Molecules held together by STRONG covalent bonds . Weak intermolecular force between molecules

3.1.2. Volatility : Low melting & boiling points since low amount of energy is required to overcome weak intermolecular forces of attractions between molecules . Hence , they are liquid /gas at r.t.p. Covalent bonds are not overcomed.

3.1.3. Electrical Conductivity : DO NOT conduct electricity AT ALL STATES as it is a NEUTRAL molecule [no free electrons]

3.1.4. Solubility : Insoluble in water except ORGANIC SOLVENT

3.2. Giant Molecular Structure

3.2.1. 3 dimensional network of atoms held together by STRONG covalent bonds

3.2.2. Allotropes : Same atoms , bonded differently

3.2.3. Macromolecular Diamond Allotrope of carbon Hardness : Very Hard - Each carbon is covalently bonded to 4 other carbon atoms in a TETRAHEDRAL structure , which makes it RIGID . Volatility : Very high melting & boiling points - solid state at room temp Electricity Conductivity : Non - conductor of electricity - No free moving electrons Solubility : Insoluble in water and organic solvent Graphite Fullerenes Allotrope of carbon Carbon atoms covalently bonded to 3 other atoms by strong covalent bonds in hexagonal rings of 6 atoms each . Volatility : Very high melting & boiling points - large amount of HEAT energy needed to break strong covalent bonds between the carbon atoms WITHIN each layer . Hardness : Soft & silppery - weak Van der Waals' forces of attraction between layers of carbon cause sliding Electricity conductivity : Good conductor - For every carbon atom , 3/4 valance electrons are used for bonding , the rest is DELOCALISED and can move . Solubility : Insoluble in water and organic solvent Silicon Dioxide Covalently bonded to 4 oxygen atoms in tetrahedral structure , while oxygen is covelently bonded to 2 silicon atoms . Volatility : Very high melting & boiling points - soiling at room temp Hardness : Very hard Solubility : Insoluble in water and organic solvent

3.3. Non-metal atoms share electrons with one another to achieve noble gas structure

3.4. Define Covalent bond : electrostatic force of attraction between the positive nucleus & shared pair of electrons . - Forming molecules

3.4.1. Molecules : 2 or more atoms held together by covalent bonds

3.5. COVALENT STRUCTURAL FORMULA : If 2 atoms shares : 1 pair of electrons [single bond] - X-X , 2 pairs of electrons [double bond] -X=X

3.6. USE SUBSCRIPT to indicate no of atoms for an element

3.6.1. Mono - 1 , Di - 2 , Tri - 3 , Tetra - 4 , Penta - 5