Nature of MatterNature of Matter

Chapter 2.1

Particles of an Atom

• Protons– Positive charge– Located in the nucleus

• Neutrons– No charge (neutral)– Located in the nucleus

• Electrons– Negative charge– Move around the nucleus

Atoms

• Basic unit of matter

• Extremely small

• Center region is called the nucleus

• Made of protons, neutrons, and electrons

Element

• Pure substance made of only one type of atom

• Each is represented by a one or two-letter symbol

• Examples – Carbon, letter C– Sodium, letter Na

Chemical Compounds

• Substance formed by combination of two or more elements

• Example – Hydrogen and Oxygen combine to form H2O (water)

Other Vocabulary Terms

• Macromolecule – made from hundreds or thousands of smaller molecules

• Monomer – smaller unit of a larger molecule

• Polymer – groups of monomers joined together

Chemical Bonds

• Ionic Bond– One or more electrons are moved or

transferred– Example – NaCl (salt)

• Covalent Bond– Electrons are shared by atoms

– Example – H20 (water)

Isotopes

• Atoms of the same element that have different numbers of neutrons

• Example– All atoms of carbon have 6 protons– However, they may have 6, 7, or 8 neutrons

Carbon

• Carbon has four electrons for bonding– Allows carbon to form four bonds

• Carbon compounds can also bond with each other to form long chains

• Carbon is used to form many of the molecules of living things