Chemistry C2 Modification

 Chemistry C2 Revision Article

C2. 1 . one particular Structure and bonding

a) Compounds will be substances by which atoms of two or more factors are chemically combined.

b) Chemical bonding involves either transferring or perhaps sharing bad particals in the highest occupied energy levels (shells) of atoms in order to achieve the electronic framework of a respectable gas.

c) When atoms form chemical bonds by transferring bad particals, they kind ions. Atoms that reduce electrons become positively recharged ions. Atoms that gain electrons become negatively incurred ions. Ions have the electronic digital structure of your noble gas (Group 0).

d) The elements in Group 1 of the periodic stand, the alkali metals, every react with non-metal factors to form ionic compounds in which the metal ion has a sole positive fee.

e) The elements in Group 7 of the periodic table, the halogens, almost all react while using alkali metals to form ionic compounds when the halide ions have an individual negative impose.

f) A great ionic substance is a huge structure of ions. Ionic compounds will be held jointly by solid electrostatic makes of attraction between oppositely charged ions. These pushes act everywhere in the lattice and this is known as ionic bonding.

g) The moment atoms share pairs of electrons, they form covalent bonds. These bonds among atoms will be strong. A lot of covalently fused substances include simple substances such as H2, Cl2, UNITED KINGDOM, HCl, INGESTING WATER, NH3 and CH4. Others have huge covalent constructions (macromolecules), such as diamond and silicon dioxide.

h) Metals consist of huge structures of atoms set up in a standard pattern.

The electrons in the highest entertained energy levels (outer shell) of metal atoms are delocalised and so free to move through the whole structure. This corresponds to a structure of positive ions with bad particals between the ions holding these people together by simply strong electrostatic attractions.

C2. 2 . 1 Molecules

a) Substances that consist of straightforward molecules will be gases, fluids or hues that have fairly low shedding points and boiling factors.

b) Substances that include simple substances have just weak causes between the elements (intermolecular forces). It is these intermolecular pushes that are overcome, not the covalent provides, when the compound melts or perhaps boils.

c) Substances that consist of straightforward molecules usually do not conduct electric power because the molecules do not have an overall electric demand.

C2. 2 . 2 Ionic compounds

a) Ionic substances have standard structures (giant ionic lattices) in which you will find strong electrostatic forces in all directions between oppositely charged ions. These substances have excessive melting items and high boiling items because of the considerable amounts of energy necessary to break the numerous strong you possess.

b) Once melted or dissolved in water, ionic compounds conduct electricity since the ions have time to move and carry the current.

C2. 2 . 3 Covalent structures

a) Atoms that share electrons can also kind giant set ups or macromolecules. Diamond and graphite (forms of carbon) and si dioxide (silica) are examples of giant covalent structures (lattices) of atoms. All the atoms in these buildings are related to other atoms by good covalent you possess and so they have very high shedding points.

b) In precious stone, each carbon atom varieties four covalent bonds with other carbon atoms in a large covalent structure, so diamonds is very hard.

c) In graphite, each carbon atom bonds to three others, developing layers. The layers have time to slip over one another because there are no covalent bonds between the levels and so graphite is gentle and slippery.

d) In graphite, one electron coming from each carbon atom is usually delocalised. These delocalised bad particals allow graphite to perform heat and electricity.

e) Carbon may also form fullerenes with different numbers of carbon atoms. Fullerenes can be used for medicine delivery into the body, in lubricants, because catalysts, and in nanotubes for reinforcing elements, e. g. in golf rackets.

C2. 2 . 4 Metals

a) Metals...

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