Composition of Matter Matter - Everything in the universe is composed of matter Matter is anything that occupies space and has mass Mass – quantity of matter an object has Volume – amount of space an object takes up.

Elements Pure substances that cannot be broken down chemically into simpler kinds of matter More than 100 elements (92 naturally occurring)

CHNOPS 6 most common elements in living things are: Carbon (C) Hydrogen (H) Nitrogen (N) Oxygen (O) Phosphorus (P) Sulfur (S) 90% or more of the mass of an organism is composed of C, H, N and O

Atoms How to draw an Atom: atom: smallest particle of an element that has the characteristics of that element basic building blocks of all matter How to draw an Atom: The Central core or NUCLEUS houses the neutrons (n) and protons (+) Electrons (-) orbit the nucleus. Why do you think this is?

The Protons All atoms of a given element have the same number of protons Number of protons called the atomic number Number of protons balanced by an equal number of negatively charged electrons

Atoms around the nucleus are the energy levels where negative electrons spin around the nucleus first energy level holds up to 2 electrons second energy level holds up to 8 electrons third energy level holds up to 8 electrons

How can you find the following? What is the relationship between an atom and an element? # of protons in an element? # of electrons in an element? # of neutrons in an element? Many atoms with the same # of protons make up elements Atomic number # of protons Atomic mass - # of protons

A compound is a pure substance made up of atoms of two or more elements bonded together The proportion of atoms are always fixed Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound

Molecules are made up of more than one atom bonded together. Some molecules are large and complex

The physical and chemical properties of a molecule differ from the physical and chemical properties of the individual elements that compose it

How do you draw an Atom to show how its electrons will bond? Bohr Diagram: shows ALL electrons with a + (#) and n (#) in the nucleus Ex: Lewis Dot Structure: shows only the VALENCE electrons around the element symbol

States of Matter Atoms are in constant motion The rate at which atoms or molecules in a substance move determines its state

Why do atoms bond? Molecule For the same reasons WE do! An Atom is typically unstable by itself It will bond to other atoms so that it can fill up its outside shell of electrons. Review: When an element bonds to become more stable it is then called a: Molecule

Covalent Bonding Electrons are shared *The Resulting Molecule is more stable than the individual atoms that it is made from. Example: H2O, CO2 and C6H12O6 http://www.youtube.com/watch?v=QqjcCvzWwww

Polarity Molecules with partial charges on opposite ends ex: H2O Polar Covalent Bonding: electrons are shared unequally, so the electrical charge is not balanced (ex: sugar) Non- Polar Covalent Bonding: electrons are shared equally by united atoms with a balanced electrical charge (ex: oil, grease, wax)

Ionic Bonding Atoms can become stable by losing or gaining electrons from other atoms. When an atom loses or gains electrons it becomes charged and is called an ION. Example: NaCl (sodium chloride) Na+ Cl-

Atoms that gain electrons are called negative ions Because positive and negative electrical charges attract each other, ionic bonds form