Bonding And Elements Essay, Research Paper

Element ? a substance which cannot be broken down

into two or more substances by any means. Only contains one type of atom. Compound ? a substance in which atoms of two or

more elements have been chemically combined. Ionic

Bonding ·

Metals bonding with non-metals ·

Involves transfer of electrons from metal to

non-metal, so that both species obtain full outer shell electron configurations

(Noble gas configuration). ·

Metals lose electrons to form positive ions

(Cations). ·

Non-metals gain electrons to form negative ions

(Anions). ·

The ions are held together by strong forces of

electrostatic attraction. The ions are held in a giant three-dimensional

regular lattice. Properties 1. High

melting and boiling points ? due to strong electrostatic forces between ions. 2. Soluble

in water (polar solvent), but not in hexane ? due to the attraction of the

atoms on the water molecules for the positive and negative ions. 3. Conduct

when molten, or in solution but not when solid ? ions are free to move when molten

or in solution. Example Sodium Chloride Na [2,8,1] Cl

[2,8,7] Na+ [2,8] Cl?

[2,8,8] Covalent

Bonding ·

Between non-metals and non-metals ·

Involves the sharing of electrons. Atoms share

electrons, so that both can achieve a full outer shell electron configuration. Two forms of covalent compounds:

simple and giant. Simple covalent compounds are

usually gases, liquids or solids with relatively low melting and boiling

points. This is because the forces between the molecules are relatively weak. Simple covalent compounds do not conduct

electricity, as there is no overall electric charge on the molecules. Examples of simple covalent

compounds: methane (CH4), ammonia (NH3), hydrogen

chloride (HCl) Methane (CH?4)? electrons from carbon

represented by x, electrons form hydrogen represented by o. This line represents a covalent bond ? shared

pair of electrons. Giant covalent structures

usually have high melting and boiling points, because the covalent bonds

themselves need to be broken. Examples of giant covalent

compounds are silicon dioxide (SiO2), graphite and diamond

(allotropes of carbon). Silicon dioxide has the same structure as diamond. Structure

and properties of diamond and graphite Diamond

Graphite In Diamond each carbon is bonded to four other

carbon atoms. In Graphite each carbon is bonded to three other

carbon atoms. It conducts electricity because it has mobile electrons between

the layers Metallic Bonding ·

Found in metals, which have giant structures. ·

An array of cations surrounded by a sea of

?delocalised? (mobile) electrons. Properties 1. High

melting point and boiling points ? the atoms are packed close together and the

bonds holding them are very strong. The energy needed to melt the metals is

high. 2. Conduct

heat and electricity ? electrons in the ?sea? are mobile. A current (flow of

electrons) can pass. 3. Insoluble

in water and organic solvents, but may react with water.