1. Chemistry Review

2. ATOMS Smallest unit of matter. –Atoms make up everything (that has mass and takes up space).

3. Protons (+) Determines the identity of the Element Represents the Atomic # Positively charged Nucleus Part of the atoms mass

4. Neutrons – No charge Neutral – No charge Nucleus Part of the atoms mass

5. Electrons (-) Negatively charged smallest particles Outside nucleus Found in the electron cloud Located in energy levels

6. Electric Charge of the Atom Overall charge of an atom is Neutral The # of (+) protons = the # of (–) electrons –They cancel each other out –Remember: Protons are positive Electrons are negative Neutrons are neutral (No charge) – They do not count

7. Atomic Particle Size

8. Nucleus Center of the atom Made up of Protons and Neutrons Makes up the atoms MASS Positively Charged!

9. Electron Cloud Area around the nucleus where electrons are found. Negatively Charged

10. Energy Levels Levels within the electron cloud that hold a specific # of electrons. –1st level - 2 electrons –2nd level - up to 8 electrons

11. Valence Electrons Electrons on the outermost energy level of the atom. Determine the atoms chemical properties, including reactivity.

12. Atomic Number Top # on the periodic table # of protons in the atom –Atomic # = 2 –2 protons

13. Chemical Symbol 1 or 2 letter abbreviation for an element name –1 st letter Capitalized –2 nd letter – always lowercase Helium - He

14. Atomic Mass Bottom # Mass of the atom Located in the nucleus Protons + Neutrons

15. Determining the # of subatomic particles in atoms Use the following A = P = E M – A = N Atomic # = Protons = Electrons Mass – Atomic # = Neutrons

16. Atom Models

17. ELEMENTS All the atoms that make up our universe Identified by the atomic # (# of protons)

18. Arrangement of the Periodic Table Elements are arranged by: 1.By increasing Atomic # and mass According to the # of protons the atom has. Increases from left to right in each period (row) 2.By metals, non-metals and metalloids According to their physical properties 3.By groups According to their valence electrons and chemical properties –Reactivity – How they react chemically in chemical reactions.

19. 3 Main Types of Elements on the Periodic Table

20. Metals Make up most of the elements All solid except Mercury Has luster (shiny) Good conductors of heat and electricity Malleable – hammered or shaped into thin sheets Ductile – stretched into wires

21. Nonmetals Usually gases or brittle solids Poor conductors of heat and electricity –They are insulators Right side of the periodic table Only 17 nonmetals

22. Metalloids Called Semi-metals Share properties of both metals and nonmetals Located on the zig-zag line between the metals and nonmetals.

23. Groups/Families 18 Vertical Columns on the periodic table Elements have the same # of valence electrons Elements share similar chemical properties including reactivity

24. Periods 7 horizontal rows on the periodic table Increase by atomic # and mass Consist of elements with the same number of energy levels.

25. Chemical Compounds A compound is when 2 or more elements chemically combine. The properties of a compound are often very different from the elements themselves. –Example: Water – H 2 O Compound with 2 hydrogen atoms and 1 oxygen atom

26. Chemical Formulas Formulas that use chemical symbols and numbers to represent what makes up a substance. –NaCl – Sodium chloride (salt) –Na – Sodium, Cl - Chlorine –H 2 O – Dihydrogen monoxide (water) –H – Hydrogen, O - Oxygen –CO 2 – Carbon dioxide –C – Carbon, O - Oxygen

27. Subscripts Numbers written below and to the right of a chemical symbol in a formula. H 2 O – 2 Hydrogen, 1 Oxygen Tells how many atoms of an element are in each molecule. Only used if more than one atom is present.

28. H 2 SO 4 How many atoms of each element are in this compound? H = Hydrogen – 2 atoms S = Sulfur – 1 atom O = Oxygen – 4 atoms How many elements are there? How many total atoms? 3 elements 7 atoms

29. Coefficients # placed in front of a chemical symbol or formula Identifies the # of molecules of a substance –2H 2 O = 2 molecules of H 2 O –3FeO 3 = 3 molecules of FeO 3

30. Coefficients X Subscripts To determine the number of atoms using coefficients you multiply the coefficient with the subscript. 2H 2 O - 2 molecules of H 2 O = 4 Hydrogen atoms and 2 Oxygen atoms

31. 2Fe 2 O 3 2 Molecules of Fe 2 O 3 = 2 X 2 = 4 Fe (iron) atoms 2 X 3 = 6 O (oxygen) atoms

32. Using Parentheses Multiply the subscript with each element in parentheses. Al 2 (SO 4 ) 3 Al = 2 atoms of Aluminum S = 3 X 1 = 3 atoms of Sulfur O = 4 X 3 = 12 atoms of Oxygen

33. Chemical Reactions Occurs when one or more substances change to produce one or more different substances. Atoms are rearranged to form a totally new substance with properties that are completely different Indicators of a chemical reaction –Gas formation –Solid formation – precipitate –Energy change – light, heat, or sound –Color change

34. Chemical Equations Uses chemical symbols and formulas to represent a chemical reaction. 2H 2 + O 2 → 2H 2 O Reactants Yield Products Sign

35. Chemical Equations Reactants –starting materials in a chemical reaction. Products –substances formed in a chemical reaction.

36. Law of Conservation of Mass The mass of atoms and molecules is neither created nor destroyed in chemical reactions. –The # of atoms for each element in the reactants must equal the # of atoms for each element in the products in a chemical reaction. –Chemical Equations must be balanced.

37. Chemical Equations Must Be Balanced! Law of Conservation of Mass The # of atoms in the reactants must equal the # of atoms in the products for each element

38. 2H 2 + O 2 → 2H 2 O Is this equation balanced? Reactants → Products H = 4H = 4 O =2O = 2 Is this equation balanced? Yes!