Chemistry  What is an atom?  An atom is the smallest unit of an element, that has all the chemical and physical characteristics of the element. All matter is composed of elements, all elements are composed of atoms.  Atoms are composed of the following particles: Nucleus  Proton – positive charge  Neutron – neutral charge Electrons – have a negative charge

Elements  What makes one type of atom different from another type of atom?  Atoms of different types are called elements.  Atoms of different elements have different numbers of protons (and electrons).

The Periodic Table of Elements 47 Ag Silver How many neutrons does silver have in it’s nucleus?

Bohr Models  Electrons are arranged around the nucleus in specific energy levels.  We can draw a diagram to show how electrons are arranged around the nucleus.  Try these:  Hydrogen, Beryllium, Carbon, Oxygen, Nitrogen, Neon, Chlorine, Aluminum, Sodium (Do activity on first 18 elements.)  Put the symbol in the box, the name, and the Bohr Model

Electrons  Have a negative charge (e-)  Travel in energy levels, which contain orbitals, around the nucleus  The first “energy level”, holds 2 electrons  The 2 nd and 3 rd energy levels can hold up to 8 electrons each  When an electron energy level is full, the next electrons fill a new higher energy level  The number of electrons = number of protons in a neutral atom  Electrons can be lost, gained, or shared when an atom bonds with another atom

The Periodic Table of Elements  It is organized!  Columns on the table are called groups  Group IA – have 1 electron in outer energy level These are soft, highly reactive metals like sodium and potassium. They loose electrons and become more positive.  Group IIA – have 2 electrons in outer energy level, they are harder, metals like calcium and magnesium. They loose electrons and become more positive.  Oxygen, chlorine, in Group VIIB, are on the right side of table – their energy levels are not full. They gain electrons and become more negative. They are nonmetals.

Why do we care about the structure of different atoms?  It helps us understand how they interact with each other to form BONDS  IONIC BONDS  COVALENT BONDS  HYDROGEN BONDS

Ionic Bonds  Ex. NaCl (table salt)  Ionic Bond – forms because of a strong attraction between oppositely charged ions.

Covalent Bond  Ex. Water (H 2 0)  Covalent Bond – A bond between two atoms formed because of sharing of electrons. Hydrogen Oxygen

Polar versus nonpolar molecules  If a molecule has a positive end and a negative end = POLAR molecule  Molecules without positive and negative ends = NONPOLAR molecule  Example – WATER is POLAR

ASPECTS OF WATER MOLECULE AND IT’S POLARITY  The arrangement or geometry of the atoms in some molecules is such that one end of the molecule has a positive electrical charge and the other side has a negative charge. If this is the case, the molecule is called a polar molecule, meaning that it has electrical poles. Otherwise, it is called a non-polar molecule. Whether molecules are polar or non-polar determines if they will mix to form a solution or that they don't mix well together

 Chemical bonding is the result of either an atom sharing one or more outer orbit electrons with another atom or an atom taking outer orbit electrons from the atom with which it is bonding. Normally, an atom has an even distribution of electrons in the orbits or shells, but if more end up on one side that the other in a molecule, there can be a resulting electrical field in that area.  Water is a polar molecule in that the way the atoms bind in the molecule are such that there are excess electrons on the Oxygen side and

 Non-polar  A non-polar molecule is one that the electrons are distributed more symmetrically and thus does not have an abundance of charges at the opposite sides. The charges all cancel out each other.

Solutions  When water dissolves a substance, the liquid is a SOLUTION  Why?  NaCl  Na+, Cl-  Na+ is attracted to?  Cl- is attracted to?

Water is important!  H 2 0 can break down into ions  H 2 0  H + + OH -  H + + OH -  H + + OH - ions are very reactive in nature

pH  When some compounds dissolve in water, ions are produced  Ex. HCl (hydrochloric acid)  HCl  H + + Cl -  Acids – adds H + ions to a solution  Ex. NaOH  NaOH  Na + + OH -  Base – adds OH - ions to a solution

pH  A measure of the amount of H + ions or OH - ions

pH Scale 

The Compounds of Life (2-2)  Organic  Inorganic

Carbohydrates

Lipids

Proteins

Nucleic Acids

Chemical Reactions & Enzymes (2-3)

Enzymes

Tryptophan – mirror image molecules

Concept Map  Use Inspiration Software to put these words into a concept map  Use linking words to connect concepts  Chemistry  Covalent Bond  Element  Atom  Molecule  Compound  Ion  Proton  Neutron Electron Atomic Number Nucleus Mass Member