Chapter 2 Notes (Day 2)

Objective: Draw a model of the atom illustrating all of the
subatomic particles and energy levels.
Atomic Structure
All things are made up of matter.
Matter is made up of atoms.
Atoms are the smallest unit of matter that can not be
broken down by chemical means.
Subatomic Particles
Proton: positive charge, located in the nucleus
Neutron: no charge, located in the nucleus
Electron: - charge, located outside the nucleus.
Electrons revolve around the nucleus in different
orbits. The closer the orbit is to the nucleus, the
fewer the electrons that can fit in that particular orbit
or energy level.
Energy Level (Orbit)
# of Electrons
Electrons move vary fast around the nucleus, forming
a hazy cloud-like appearance to the atom. Therefore,
the location of the electrons is often called an
electron cloud.
Elements and Such
Elements: substance made up of only one type of atom.
Example: Carbon
Compound: Substance made of joined atoms from 2 or
more different elements.
Example: Carbon Dioxide (CO2) = 1 carbon + 2
Molecule: A group of different atoms held together by
covalent bonds
Example: H2O and O2
Chemical Bonds
It is important to remember that compounds are the
most stable or happy when their outer energy level is
filled with electrons.
1.Covalent Bonds: forms when 2 or more atoms share
electrons. Neither atom truly has possession of the
Example: H2O
Hydrogen Bonds: Very weak bonds, easy to break. They form
between a positively charged Hydrogen atom from one covalently
bonded molecule to a negatively charged portion of another
covalently bonded molecule.
* Polar molecules: have a positive and negative charge.
Example: H2O
* Hydrogen side of molecule has a + charge
Oxygen side of molecule has – charge.
Ionic Bonds: Created by oppositely charged ions.
* Ion: Occasionally atoms or molecules will gain or lose an
electron to fill its outer energy level. The atom or molecule
becomes + or – charged. This is an ion.
Oppositely charged ions can bond to form an ionic bond.
Example: NaCl (salt)