 The basic unit of all matter  Small in size

 Proton  Neutron  Electron

 Proton and Neutron – NUCLEUS of the atom (center)  Electrons – found rapidly moving in energy levels (energy clouds)

 Proton = Positive (+)  Neutron = Neutral (0)  Electron = Negative (e-)

 Proton  Neutron  Remember – the electrons are SOOOO LIGHT that they are not part of the mass (atomic weight)

 There is an equal number of protons and electrons  If there are more protons – then the atom would have an overall POSITIVE charge  If there are more electrons – then the atom would have an overall NEGATIVE charge

 Use the terms ◦ Symbol ◦ Atomic Weight (Mass) ◦ Atomic Number

A Atomic Number Symbol Atomic Weight (mass)

 Hydrogen  Oxygen  Nitrogen  Carbon  There is also phosphorus and sulfur, but I only want you to focus on the four listed above.

 The symbol for Krypton is  The mass number for Calcium is  The atomic number for Beryllium is

 The symbol for Krypton is Kr  The mass number for Calcium is  The atomic number for Beryllium is 4

 The number of molecules present  LARGE NUMBER written before the element symbol  Ex: 4CO 2  There are 4 molecules of carbon dioxide

 The number of atoms present  SMALL NUMBER written within the chemical formula  Ex: 4CO 2  There are 8 atoms of oxygen  Remember to distribute (4 x 2=8)

 5C 2 H 4  How many molecules are present?  How many atoms of Carbon are present?  How many atoms of Hydrogen are present?  How many TOTAL atoms are present?

 5C 2 H 4  How many molecules are present? 5  How many atoms of Carbon are present? 10 (5x2 – remember to distribute)  How many atoms of Hydrogen are present? 20 (5x4 – remember to distribute)  How many TOTAL atoms are present? 30 (distribute and then add up) (5x2) = 10 (5x4) = = 30

 A. Electrons  B. Protons  C. Neutrons  D. Valence Electrons

 A. Electrons  B. Protons  C. Neutrons  D. Valence Electrons  Choice D is the most accurate answer here

A. Gained B. Lost C. Shared

A. Gained B. Lost C. Shared

 In the outermost energy level of an atom

 8 electrons!

 8 – OCTET rule ◦ The outermost energy level will be complete when it contains 8 electrons. ◦ Atoms will gain/lose/share electrons to reach this stability!  ****EXCEPTION**** ◦ Hydrogen and Helium follow the DUET RULE (can only have 2 electrons in the outermost shell to be stable and unreactive)

A. Carbon B. Neon C. Helium D. Magnesium

A. Carbon – 4 opportunities to bond (vacancies) B. Neon C. Helium D. Magnesium – 6 opportunities to bond (vancancies) Neon is stable because it is a noble gas – already has 8 electrons Helium is stable because it is also a noble gas – but follows duet rule so it has 2 electrons

 Single Bond  Double Bond  Triple Bond

 Single Bond ◦ Atoms share 2 electrons (1 pair)  Double Bond ◦ Atoms share 4 electrons (2 pairs)  Triple Bond ◦ Atoms share 6 electrons (3 pairs)

 Types of Elements  Number of atoms  Location of atoms Example –  1 Oxygen  2 Hydrogen

 COVALENT BONDS  SHARING OF ATOMS!!

 Phosphorus  Hydrogen  Nitrogen  Oxygen

 Phosphorus  Hydrogen  Nitrogen  Oxygen

 WATER

 Changes or transforms one set of chemicals into another  CHANGES to the BONDS – breaking and reforming bonds

 Reactants  Products

 Reactants ◦ ENTER into a chemical reaction (before the arrow)  Products ◦ PRODUCED by a chemical reaction (after the arrow)

 Reactants  Products  Coefficients  Subscripts

 C - Reactants  D - Products  A - Coefficients  B – Subscripts  Reactants REACTto produce PRODUCTS

 Matter cannot be created nor destroyed  Arrangement of atoms is what is changed  Reactants must equal products

 Na + Cl 2  NaCl

 ANSWER - NO  2Na + Cl 2  2NaCl