unit 7 summary. IES Auringis Jaen Spain

3. Inorganic chemistry: the study of inorganic matter.

4. Organic chemistry: the study of organic (carbon based) matter.

5. Biochemistry: the study of substances found in biological organisms.

7. Element is a substance which is composed of a single type of atom. A chemical element is characterized by a particular number of protons in the nuclei of its atoms (the atomic number ). For example, all atoms with 6 protons in their nuclei are atoms of the chemical element carbon, and all atoms with 92 protons in their nuclei are atoms of the element uranium.

8. Compound is a substance with a particular ratio of atoms of particular chemical elements which determines its composition, and a particular organization which determines chemical properties. For example, water is a compound containing hydrogen and oxygen in the ratio of two to one.

9. Strictly speaking, a mixture of compounds, elements or compounds and elements is not a chemical substance, but it may be called a chemical or a mixture . Most of the substances we encounter in our daily life are some kind of mixture; for example: air, alloys, biomass, etc.

11. Element: a chemical element is a substance which is composed of a single type of atom. It is characterized by a particular number of protons in the nuclei of its atoms. This number is known as the atomic number of the element. For example, all atoms with 6 protons in their nuclei are atoms of the chemical element carbon, and all atoms with 92 protons in their nuclei are atoms of the element uranium.

12. Isotopes are atoms of one element (same number of protons in their nuclei) with a different number of number of neutrons.

13. Ion is a charged atom (or a molecule), that has lost or gained one or more electrons. Positively charged: cations (e.g. sodium cation Na+). Negatively charged: anions (e.g. chloride Cl−)

16. The octet rule is a simple chemical rule that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells , giving them the same electronic configuration as a noble gas.

17. An ionic bond , the bonding electron is not shared at all, but transferred. In this type of bond, the outer atomic orbital of one atom has a vacancy which allows addition of one or more electrons. These newly added electrons potentially occupy a lower energy-state (effectively closer to more nuclear charge) than they experience in a different atom. Thus, one nucleus offers a more tightly bound position to an electron than does another nucleus, with the result that one atom may transfer an electron to the other. This transfer causes one atom to assume a net positive charge, and the other to assume a net negative charge. The bond then results from electrostatic attraction between atoms, and the atoms become positive or negatively charged ions.

19. Metallic bonding is the electromagnetic interaction between delocalized electrons, called conduction electrons and gathered in an "electron sea", and the metallic nuclei within metals. Understood as the sharing of "free" electrons among a lattice of positively charged ions (cations). Metallic bonding accounts for many physical properties of metals, such as strength, malleability, ductility, thermal and electrical conductivity, opacity, and luster.