1. Chemistry Intro
ancient thinkers said there must be a smallest part that stuff is made up of, this was called the atom
scientists discovered that atoms are actually made up of smaller particles
Proton:
Neutron:
Electron:
Linked

2. most of the atom is empty space where electrons move
atoms have equal number of electrons and protons so there are overall charge is zero
electrons stay around nucleus because of positive/negative attraction with protons
most of the atom is empty space where electrons move
LinKed

3. e- are found in energy levels (specific distance from nucleus) & sublevels (orbital or movement shape/pattern)
e- move in complicated patterns determined by attractive force of nucleus
to be stable (“happy”) ALL atoms want 8 e- in their outer most (valence) energy level

4. Element - pure substance that cannot be broken down into simpler substances

5. Practice:

6. Periodic Table of Element
Horizontal rows gives # of energy level of electrons
Blocks give sublevel (electron orbital shapes)
Linked

7. valence – outer most energy level

8. Isotopes
Most elements are uniform mixtures of 2 or more unique substances called isotopes.
Isotopes of an element have very similar chemical properties but their atoms have slightly different masses
What about the different atoms, of the same element, could make their masses different??? _________________
__________________________________________________
Linked
BrainPOP

9. Compound is a pure substance that
is made from 2 or more different elements chemically combined
are always formed from a specific combination of elements in a fixed ratio
cannot be broken down into simpler compounds or elements by physical means.

10. Molecules & Chemical Formulas
Atoms are identified by their elemental symbol within a formula
Subscripts tell how many atoms of that element are present in the compound/molecule
i.e.) “urea” - CO(NH2)2 [from Wikipedia ”Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals”]
C: 1
O: 1
N: 2
H: 4

11. Practice How many atoms of each element are there in each formula?
KHCO3 H2SO4
(NH4)2SO4 (CH3)3COH

12. What keeps atom together to make compounds?

13. All atoms want a full valence shell (8)

14. Atoms with less than 4 valence will give electrons away to make 8
Atoms with more than 4 valence will take electrons from others to make 8
ion – atom got charged
so it could get 8 valence
cation – positive charge
anion – negative charge

15. Ionic Bonding
Oppositely charged ions attract (the attraction “glues” the ions together) and is called “ionic bond”

16. Examples Mg N Al O

17. What happens when neither atoms wants to give valence electrons
What happens when neither atoms wants to give valence electrons? How can each get 8??? _______________________________________________
shared e- “belongs” to both atoms
both valences are full
valence energy levels of overlap
the sharing/overlap binds the atoms together and is called a covalent bond
Linked

18. Examples C
CH4 H
C2H2

19. What about water? Formula for water ______
Water is called the universal solvent
(“can dissolve a lot of stuff”)

20. Why can water dissolve so much stuff???
dipole-dipole attraction cause water molecules to surround and isolate sugar molecules
ion–dipole attraction separates NaCl formula units into isolated ions

21. When sharing, why would one interacting thing get more than another

22. Molecular (“Pull”) Polarity
Stronger atom PULLS electrons toward its-self
Creates area with more electrons (negative charge)
Thus, the molecule becomes partially charged
Has an area that is a little negative and another area that is a little positive
water is polar (“puller”)

23. Polarity results in …. Intermolecular (Van der Waals) Forces
Dipole-Dipole of one molecule attracts to the of another

24. Hydrogen bonding
dipole-dipole attraction of H in a polar bond to an F, O, or N in another molecule
H bonding is stronger than regular dipole-dipole due to an unshared electron pair
Linked

25. Van der Waals forces of water(linked)
cohesion (molecules sticking together) causes water to form drops that are nearly spherical, and adhesion ( molecules sticking to another substance) keeps the drops in place
Capillary action – ability of water to flow up a thin tube without assistance against gravity

26. Mixture -combination of two or more substances (called components) each retaining its individual identity and properties
M&M’s “look” different (linked)
Heterogeneous– mixture that looks
different & is different
Homogeneous – mixture that looks the same BUT is different
solution – evenly distributed homogeneous mixture
Solute – part that “does the dissolving”
Solvent – part that gets “dissolved”
sugar -
water -
Coffee with cream & sugar looks the same

27. Changes in Matter
Physical change – alters a substance without changing its composition
may result in drastically different appearance BUT composition of substance remains unchanged
Examples:
H2O H2O H2O

28. H+ + O H-  Acids & Bases Acid – substance that releases H+ in water
Base – substance that releases OH- in water
H O H- 
strength of acid/base measured by pH = -log [H+]
the more H+ the more acidic BUT the lower the pH
linked

29. Changes in Matter What is a chemical change?
matter is neither created nor destroyed
new substance(s) are made from rearrangement of atoms
How do you know new substances have been made?
will have new physical properties

30. Changes in Matter
Chemical change (“reaction”)– a process that involves one or more substance changing into new substances
substances formed after change have different compositions & properties from those present before
Examples:
Linked

31. Writing Chemical equations
We use formulas and symbols to describe a chemical rxn
If substance A is mixed with substance B and the two undergo a chemical change that produces substances C and D we write:
A + B  C + D
A and B are called the reactants (left side of arrow)
C and D are called the products (right side of arrow)

32. Balanced Chemical Equations
Glucose and oxygen react to produce carbon dioxide and water
C6H12O O2  CO H2O
coefficient – BIG number written in front of reactant/product
tells you # of molecules
What about the law of conservation of matter???
tells you # of atoms