More General Science Questions

13. Chemical changes are changes which completely alter the chemical makeup of the substance. There is a release or absorption of energy, and sometimes gas is released or a color change occurs. Wood burning is a chemical change, because the chemical makeup of the wood is different from the ashes resulting from the fire. Physical changes are changes to only appearance, size or phase. Ice melting into water, or water evaporating into gas are all physical changes; ice, water and water vapor are all still H20.

14. Water is essential to life on earth because water has properties that no other material has. Water is expands when it is both hot and cold, is liquid as at room temperature unlike most substances, has an uneven distribution of electron and is slightly charged on both ends, therefore allowing water to form mixtures, solutions and suspensions easily.

15. Matter is solid and moves as particles. They have physical properties like color, shape, mass, weight and chemical properties. Energy moves as waves as heat and light. Metabolism is the rate at which you use energy.

16. Matter and energy are moved by living things and the elements. Heat and light allows things to grow and spreads solar energy up through the food pyramid.

17. Atom-smallest single particle of matter; elements-matter consisting of one type of atom; compounds-the combining of two or more different elements; molecular weight-the weight of the atom. An ion is a charged particle, a molecule is the combination of atoms whose results forms a separate particle, a compound is a mixture of atoms.