Main Idea: All living things are based on atoms and their interactions

Atoms are: Building blocks of all matter NOT living Similar in structure

Atoms are made of 3 types of subatomic particles Protons + Neutrons Electrons - Electrons Protons Neutrons

Nucleus of an Atom Nucleus is the core of an atom. It contains : N Protons Have a positive charge Each type of atom has a specific number of protons (Atomic Number) N eutrons Have no charge / neutral N N Nucleus

e-e- e-e- Electron Cloud of an Atom The electron cloud is the area that surrounds the nucleus and contains electrons orbit the nucleus of the atom Electrons : have a negative charge Electron Cloud

Atom Structure +1 Electron Proton Neutron +1

Subatomic Particle Charge Location

Subatomic Particle Charge Location Proton + Positive Nucleus Neutron No Charge Neutral Nucleus Electron - Negative Electron Cloud

 Atoms have a balance of positive protons and negative electrons which gives them an overall neutral charge

+ - An atom or group of atoms that has an electrical charge because it has gained or lost electrons

+ -  An atom can never lose or gain protons because that is its “identification number”.

+ - BUT An atom CAN lose or gain its electrons. When they do, they become ions.

Remember – Electrons have a negative charge. If an atom “loses negativity ” it becomes “more positive” If an atom “gains negativity” it becomes “more negative”

Positive Ions are written with a positive sign. Ex. H+ Negative Ions are written with a negative sign. Ex. OH-

An atom that does NOT gain or lose electrons has a Neutral charge. It is NOT an ion. Its number of negatively charged electrons is equal to /balanced by the number of positively charged protons. Neutral atoms are written without a sign. Ex. Ra

Atomic Combinations Main Idea: Atoms join to form elements and compounds

Element A substance that is made of one or more of the same type of atom. Examples include : O2 – Oxygen we breath O - Oxygen atom 0 3 – Ozone molecule

Periodic Table of Elements

Element Symbols Each element is represented by its elemental symbol – a 1-3 letter abbreviation with 1 st letter capitalized

Compound A substance made of two or more different elements

Hydrogen atoms - green Oxygen atoms - black Water Molecule Hydrogen Peroxide Molecule

2 Categories of Compounds – based on whether they contain carbon atoms Compounds that : DO contain carbon atoms - organic compounds DO NOT have carbon atoms- inorganic compounds  Carbon Dioxide – CO 2  Water – H 2 O

 Isomers – molecules that have the same type and number of elements but are arranged differently

Lesson Topic: Chemical Bonding Main Ideas: *Atoms are joined by bonds to form elements and compounds *Bonds involve the atom’s electrons

Electrons are found in “energy levels ”

* Each “energy level” only holds a certain number of electrons E level one - 2 electrons E level two - 8 electrons E level three - 8 electrons

Atoms are reactive (likely to bond) when there aren’t enough valence electrons to fill their outermost energy level. Atoms gain, lose or share valence electrons to fill the level.

Ionic Bonds  Attractive force between oppositely charged ions.  Ion – a charged atom due to gaining or losing electrons.

Compounds formed between Ionic bonds are called ionic compounds. Sodium chloride crystal (NaCl) – Table salt

How Ionic Bonds Form

Covalent Bonds Atoms share electrons. Compounds formed by covalent bonds are called molecules.

Single covalent bond – each atom shares one of its valence electrons Single bonds - Methane

Double covalent bond – each atom shares two of its valence electrons Double bonds

Bond energy -the measure of bond strength in a chemical bond. It is the amount of heat E required to break the molecule into its individual atoms. Covalent bonds are stronger than ionic bonds – takes more bond energy to break them apart

Ionic Bonding