Chemical Bonding Revision Notes

Bartley Secondary School Science Department Name: ______________________ Class: ______________

Date: _____________

Revision notes on Chemical Bonding Atoms lose or gain electrons to achieve a stable octet structure. (8 valence electrons)  Metal atoms  give away electrons positive ions (cations)  Non-metals gain electrons  negative ions (anions). Ionic bonding • Occurs when a metal atom combines with a non-metal atom • Formed by TRANSFER OF ELECTRONS FROM A METAL ATOM TO A NON-METAL ATOM • Occurs between ions of opposite charges attracting each other Transfer of electrons

Covalent bonding • Occurs mostly between non-metals • Formed by SHARING OF ELECTRONS between two atoms. Sharing of electrons

Prepared by Miss Syikin, 2007.

Bartley Secondary School Science Department Differences between ionic and covalent compounds. Property Electrical conductivity Melting and boiling points Solubility in water Solubility in organic solvents

Ionic compound Covalent compound Conducts electricity when Does not conduct molten or dissolved in electricity in any state water High Low Mostly soluble Mostly insoluble

Mostly insoluble Mostly soluble

List of common cations and anions Cations (positive ions) Ammonium ion NH4+ Aluminium ion Al3+ Calcium ion Ca2+ Copper (I) ion Cu+ Copper (II) ion Cu2+ Hydrogen ion H+ Iron (II) ion Fe2+ Iron (III) ion Fe3+ Magnesium ion Mg2+ Sodium ion Na+ Potassium ion K+ Zinc ion Zn2+

Prepared by Miss Syikin, 2007.

Anions (negative ions) Chloride ion ClFluoride ion FBromide ion BrIodide ion INitrate NO32Sulphate SO42Oxide O2Hydroxide OH-

Bartley Secondary School Science Department Name: ______________________ Class: ______________

Date: _____________

Revision Practice 1. The electronic structure of sodium and chloride atoms are respectively 2.8.1 and 2.8.7. (a) What is the valency of chlorine in sodium chloride? ……………………………………………………………………………………… (b) (i) Draw the electron arrangement of the particles formed when an atom of sodium reacts with an atom of chloride.

(ii) What is the name given to this type or bonding? ……………………………………………………………………………………… (iii) How does this bonding help to explain the high melting point of sodium chloride? ……………………………………………………………………………………… ……………………………………………………………………………………… 2. The electronic configuration of a sulphur atom is 2.8.6. (a) Write in the same way, the electronic configuration of the atoms of carbon and oxygen. Carbon ………………………………..

Prepared by Miss Syikin, 2007.

oxygen ……………………………

Bartley Secondary School Science Department (b) Draw a diagram showing the electronic arrangement in a molecule of carbon dioxide.

3. Three properties of five substances are shown in the table below. Each substance is represented by a letter. Substance

Melting point /°C

V W X Y Z

1083 870 -23 2027 98

Electrical conductivity Solid liquid Good Good Nil Good Nil Nil Nil Nil Good Good

State the letter of a substance which is: (a) a solid at 1100°C

………………

(b) ionically bonded

………………

(c) most likely to be soluble in water

………………

(d) composed of small, cavalently-bonded molecules

………………

4. Complete the following table; Formula (a) sodium chloride (b) carbon monoxide (c) water (d) methane (e) copper (II) oxide

Prepared by Miss Syikin, 2007.

Type of bond