1. Elements, Compounds and Atoms Oh My!

2. Element An element is the simplest type of substance with unique physical and chemical properties. An element consists of only one type of atom. Each element is unique

3. Atom The smallest particle of an element that retains the chemical nature of the element. A neutral, spherical entity composed of a positively charged central nucleus surrounded by negatively charged electrons.

4. Atom

5. Molecule Is a structure consisting of two or more atoms that are chemically bound together and thus behaves as an independent unit Eg. Oxygen gas occurs in air as diatomic molecules

6. A compound A compound is a substance composed of two or more elements that are chemically combined A compound can be broken down into its component elements

7. Atoms of an element

8. Molecules of an element

9. Molecules of a compound

10. Chemical Formula In a chemical formula, element symbols and numerical subscripts show the type and number of each atom present in a unit of substance. There are several types of chemical formula: Empirical formula Molecular formula Structural formula

11. Empirical Formula Shows the relative number of atoms of each element in the compound. It is the simplest type of formula Taken from the masses of the component elements Eg. Empirical formula of hydrogen peroxide is HO

12. Molecular Formula Shows the actual number of atoms of each element in a molecule of a compound. E.g. Hydrogen Peroxide H 2 O 2

13. Structural Formula Shows the actual number of atoms and the bonds between them i.e. the arrangement of atoms in the molecule.