Hello!
1) Chemistry-the study of matter, how it is classified, and how it changes
Chemistry was developed from Alchemy, a philosophical discipline which combined elements of metallurgy, physics, and biology, among others, but without the use of the scientific method. Chemistry emerged as a distinct science from the studies of Antoine Lavoisier, a French scientist who is called "The Father of Chemistry".
2) Atom-the simplest unit of an element that still retains the properties of that element
There are many different ways in which chemists along the ages have tried to describe atoms. There are models like the Dalton Atomic Model, which describes atoms as spheres, or the Schrodinger Atomic Model, which describes atoms as a nucleus surrounded by electrons in probability clouds (This is the most current atomic model).
3) Element-a primary substance that cannot be divided into separate substances; one of about 112 different basic varieties of matter making up the universe.
Differences between elements are based mainly on their electron configurations. Elements are grouped together in the periodic table in what is called a "Group", Elements within the same "group" have similar electron configuration and have very similar properties too. For example, Sodium (Na) and Potassium (K) are in the same group and have very similar properties.
4) Molecule-one or more elements chemically joined together such that the elements have lost their individual identity in favor of a new set of properties
Molecules are formed when atoms are involved in a chemical bond. Chemical bonds form in chemical reactions. There are molecules of two units of the same element, e.g. Oxygen (O₂), Chlorine (Cl₂) or Hydrogen (H₂). There are also molecules of different elements, as Water (H₂O), Acetic Acid (CH₃COOH) or Sodium Chloride (NaCl).
5) Compound-two or more elements chemically joined together such that the elements have lost their individual identity in favor of a new set of properties
Compounds are different from molecules in the sense that Compounds are only formed, as their name says, of two different elements. All compounds are molecules but not all molecules are compounds. Some common compounds are Carbon Dioxide (CO₂), Sulphuric Acid (H₂SO₄) or Hydrochloric Acid (HCl), among many others.
6) Mixture-two or more substances dispersed in one another but each retaining their own identity
In a mixture, two distinct substance are together. In a homogeneous mixture, the substance that is in the higher amount is called the solvent, and the substance that is in the lower amount is called the solute. Although the two substances retain their own identities, the mixing of them gives them properties that they do not have on their own e.g. a mixture of salt and water has properties that are very different from water only.
7) Product-a substance formed as a result of a chemical reaction
Chemical Reactions can have different kinds of products. Sometimes the product can be an atom, as in the reduction of iron oxides to produce iron (2Fe₂O₃ + 3C → 4Fe + 3CO₂), or sometimes the product can be a molecule or compound, as in the case of the formation of water from the oxidation reaction of H₂ (2H₂ + O₂ → 2H₂O).
Have a nice day!
