1. Chemistry Review Chapter 2

2. Matter
Anything that takes up space and has mass

3. Element Substance that cannot be broken down to other substances
25 are essential to life
The following list contains the elements you should know for this course

4. 96% of Living Things C H O N
Carbon
Hydrogen
Oxygen
Nitrogen

5. Other Important ElementsCa K Fe I Na Cl Mg
Phosphorus
Sulfur
Calcium
Potassium
Iron
Iodine
Sodium
Chlorine
Magnesium

6. Table 2.1 Naturally Occurring Elements in the Human Body

7. ATOM
Smallest unit with physical and chemical properties of an element

8. Chart of Subatomic Particles
Mass
Location
Charge
Proton
1 dalton
Nucleus +
Neutron
Electron
1/2000 dalton
Orbitals -

10. Atomic Number Mass Number Isotope
number of protons in nucleus (also tells the number of electrons)
Mass Number
number of protons and neutrons
Isotope
element with same number of protons but different number of neutrons

11. Carbon has three isotopes
Carbon 12 - most common (6P and 6N)
Carbon % in nature (6P and 7N)
Carbon 14 - very small amounts (6P and 8N)
this is a radioactive isotope used in carbon dating and as tracers in medicine)

13. Energy
Ability to do work

14. Potential energy stored energy due to position
person sitting on top of slide or electrons far from nucleus

15. Energy levels (electron shells)
Electrons closest to the nucleus have the lowest energy
Electrons can move to other energy levels only in steps by absorbing or losing energy
Figure 2.9 CD

16. Examples
In photosynthesis light excites an electron to a higher energy level
When light hits your car, it excites e- in the paint and as they fall back to their regular energy level they release heat -OUCH!!

17. Valence Electrons
Electrons in the outermost energy shell (these will be used for bonding)
If the outermost shell is full, the element is unreactive
If the outermost shell is not full, it is unstable and will try to fill it’s shell by gaining or losing electrons

18. Valence
The bonding capacity of an atom (how many electrons it will gain or lose in order to make it stable)

19. Remember, the first shell holds 2 electrons, and the others hold 8
You can use the atomic number to determine how many electrons are in the outermost shell.
Remember, the first shell holds 2 electrons, and the others hold 8

20. Example The atomic number for oxygen is 8 (8 protons and 8 electrons).
If you draw in the electrons, the first shell gets 2, the next shell gets 6.
It has 6 valence electrons.
To make it stable, it is easier to gain 2 electrons than to lose 6. This means the valence for oxygen is 2.

21. Try the following elements
Boron (5)

22. Chlorine (17)

23. Sodium (11)

24. Hydrogen (1)

25. Figure 2.10 Electron configurations of the first 18 elements

26. Chemical bonds
Interaction between atoms that aid in filling the valence shell

27. Covalent bond Sharing a pair of valence electrons ex- CH4 - methane
Nonpolar covalent - equal sharing of electrons
ex- CH4 - methane
Polar covalent - unequal sharing of electrons due to electronegativity. The most electronegative atom will pull the electrons closer to it resulting in a slight (-) charge
ex-- water molecules

28. Figure 2.12 Covalent bonding in four molecules

29. Figure 2.13 Polar covalent bonds in a water molecule

30. Ionic bond
Complete transfer of electrons resulting in charged atoms (opposite charges attract forming a bond)
ex. NaCl
anion - negatively charged atom (ion)
cation - positively charged atom (ion)

31. Figure 2.14 Electron transfer and ionic bonding

32. Hydrogen bonds
Occurs when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.
ex-- water molecules to each other

33. Figure A hydrogen bond

34. Chemical Reactions
Making or breaking of chemical bonds leading to changes in composition of matter.

35. Label the reactants and products in the equation below
C6H12O6 + 6O > 6CO2 + 6H2O
Reactants Products
(first one to name the reaction gets extra credit)

36. Respiration!!!