Ch. 2Part 1

Chemical Level of Organization

Chemistry Review

• You should already know this! If you don’t, make notes.

• What are:atoms nucleus protonsneutrons electrons energy levelsatomic number mass number moleculecompound cation anionionic bond covalent bond chemical reactionreactants products

Atoms

• Atoms – smallest units of matter

• Have a nucleus – center– Protons – positive, live in

nucleus– Neutrons – neutral, live in

nucleus– Electrons – negative, live in

energy levels

Periodic Table

Periodic Table

• Atomic number – big number on periodic table, tells the number of protons

• Mass number – small number on periodic table, tells the number of protons + neutrons

• IN A NEUTRAL ATOM – the number of protons = the number of electrons

• Practice– Neon, gallium, zirconium, chlorine

Compounds vs. Molecules

• Compound – contains 2 or more different elements– Examples – H2O, NaCl, MgCl2

• Molecules – contains 2 or more atoms that share electrons– Examples, H2O, O2

Bonding

• 2 Types – ionic and covalent• Ionic bonds – occur between ions, atoms

give/take electrons• Covalent bonds – occur between atoms,

atoms share electrons

Ionic Bonds

• Ions give or take electrons• Cations - + ions• Anions – ions• When put together properly, compound

should be neutral• Practice: sodium and chlorine– Na is a cation (Na+), chlorine is an anion (Cl-)– NaCl

Covalent Bonds

• Atoms share electrons• Must meet the octet rule – each atom must

have 8 electrons• Use Lewis structures for help• We will not worry about bonding angles or

shape