Chemical Structures


  • Created by: Belinda
  • Created on: 01-06-11 11:06

Covalent Bonds & Covalent structures - simple mole

Covalent bond=very strong bond between non-metals where electrons are shared

A single convalent bond = when two atoms share one pair of electrons, each atom shares one electron in the bond

A double covalent bond = when 2 electrons are shared

A triple covalent bond = When 3 electrons are shared

Examples of covalent compounds: Hydrogen chloride, carbon dioxide, water

Simple covalent structures are molecules with few atoms. they have strong forces between the atoms but weak intermolecular forces

so simple molecules have low melting and boiling points and no overall charge so can't conduct electricity

Covalent molecules can dissolve in non-aqueous solutions

1 of 6

The halogens

They are diatomic molecules (contain 2 atoms which are covalently bonded by a pair of electrons

The attraction between chlorine molecules is weak so melting and boiling points are low. Chlorine = gas at room temp

Attraction between bromines molecules is weak, its melting and boiling points. bromine = liquid at room temp

The intermolecular forces of Iodine are strong. It boils at 184 degrees but still the covalent bonds don't break

2 of 6

Covalent structures - giant molecules & Bonding in

Giant covalent structures have many atoms

Diamond is lattice where each carbon atom forms four bonds, it has high melting and boiling points and can't conduct electricity

Graphite is lattice each carbon atom forms three covalent bonds. It's in a layered structure, the layers slide past each other. It has high melting and boiling points. It can conduct electricity.

Metal atoms form giant crystalline structures. Atoms are packed together tightly so the outer electrons get separated from the atom.

Metals conduct electricity well because the electrons move freely within structure and carry electric the charge

3 of 6

Other carbon structures and uses of carbon structu

Buckminster Fullerenes (bucky balls) = Carbon 60

Unsaturated carbon-carbon bonding
Stronger than diamond
Returns to its orginal shape
Spins at high speeds
Not very reactive, can be dissolved

Caron nanotube = half an atom of a buckyball
it is the strongest form of carbon, it is flexible and can bend up or down to contact an electrode

Uses of carbon structures:
conduct electricity
Transistors and diodes
Ion storage for batteries
Reinforcemtn in buildings
Industrial catalysts

4 of 6

Chemical-based therapy & How medicines work

Chemical-based therapy = a form of medication taken to alleviate (relieve) symptons of an illness or ailment E.g:

  • Chemotherapy - used to treat cancer and to stop the spreading of cancer, it is very effective
  • Antibiotics - used to destroy bacteria

Most medicines replace substances that are deficient or missing in the body

Medicines can alter the activity of cells

They can destroy infectious microorganisms or abnormal cells

5 of 6

Homeopathic Medicine & Argument against Homeopathy

Homeopathic treatments = Medicines that alter the activity of cells

They use weak, diluted doses of compounds or drugs that would cause symptoms of the illness in a healthy person

This causes the body to kickstart the natural healing process

Each homeopathic medicine is tailored to the individual patient

Some scientist believe that homeopathic medicines just have a placebo effect

Homeopathic medicines are inert so have a short term effect on the patient

Some scientists believe that the laws of physics and chemistry would need to be re written in order to make sense of how homeopathy works

6 of 6


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Structure and bonding resources »