Science

Whenever 'work' is done energy is transferred from one place to another

work done = force x distance.

Power is a measure of how quickly work is being done.

power = work done / time taken.

A covalent bond is formed between non metal atoms, which combine together by sharing electrons.

The covalent bonds binding the atoms together are very strong but there are only very weak forces holding the molecules to each other (the intermolecular forces). Therefore, only a small amount of energy is needed to separate the molecules this is why they have a low melting point.

Covalent compounds have no free electrons and no ions so they don't conduct electricity.

The period number is the same as the number of electron shells that are occupied.

The group number is the same as the number of electrons in the outer shell of all the elements in the group.

Hallucinogens:LSD, cannabis

Hydrochloric acid is another substance (as well as enzymes) that helps digestion in the stomach.

Ecological niche:animals that live in the same habitat and have same position in the food web.

CFCS:cause ozone pollution

Exponential growth:ever-incresing rate