Midterm Study Guide

1. Definition of chemistry a. The study of the composition of matter 2. Difference between a theory and a law b. Theory- is as good as the information you have at that moment and it cannot be proven c. Law- is always true and can never be proven wrong 3. Physical vs. Chemical properties d. Physical Properties- observed and measured without changing the substance e. Chemical Properties- observed and measured while changing the substance 4. Chemical vs. Physical changes f. Chemical Change- changing the composition of a substance g. Physical Change- changing the outside or the appearance of a substance
5. Putting numbers into and out of scientific notation
6. Difference between precision and accuracy

7. Be able to perform metric conversions K | 10^3 | d | mL = cm^3 mL = cm^3
10^-1 | c | 10^-2 | m | 10^-3 | μ | 10^-6 | N | 10^-9 | M | 10^6 |

8. Be able to find density
M
M

V
V
D
D

9. Know Dalton's Atomic Theory a. All elements are composed of tiny indivisible particles called atoms (FALSE) b. Atoms of the same element are identical. Atoms of any one element are different from those of any other element (FALSE) c. Atoms of different elements combine in simple whole number ratios to form chemical compounds (TRUE) d. In chemical reactions, atoms are combined, separated, or rearranged- but never changed into atoms of another element (TRUE)
10. Models of the atom a. Plum Pudding- electrons float around in a positive charged “pudding” b. Nuclear Model- atom is mostly empty space. All the positive charge and almost all the mass is concentrated in a small area in the center, called the nucleus. Nucleus is composed of protons and neutrons c. Planetary- electrons orbit the nucleus like planets d. Quantum-atom is found inside a blurry electron cloud
11. Scientists – Thomson, Rutherford, Millikan, etc.
Democritus- He believed that atoms were tiny, indivisible and indestructible.
Thomson- used a cathode ray tube to find the presence of a negatively charged particle: the electron
Rutherford- Discovered dense positive piece at the center of the atom- “nucleus” by using the gold foil experiment
Dalton-Atomic theory
Millikan- determined the mass of the electron by using an oil drop apparatus
Chadwick- confirmed the existence of the “neutron”
Goldstein- observed what is now called the “proton”
Bohr-Electrons move like planets around the sun.
Schrodinger- derived an equation that described the energy and position of the electrons in an atom
Heisenberg- You can find out where the electron is, but not where it is going. OR… You can find out where the electron is going, but not where it is!

12. Ions, Isotopes, Atoms a. Isotope- Electrons and Protons are the same , but the number of neutrons makes your mass different b. Ions- an atom that has a positive or negative charge c. Atoms- neutral because the number of protons equals electrons
13. Be able to find numbers of protons, electrons, and neutrons
14. Rules for electron configuration and exceptions
15. Light equations * C= speed of light * V= frequency * E= energy * ʎ= wavelength
16. Periods vs. Groups a. Periods- horizontal rows b. Groups- vertical columns
17. Periodic trends and reasons behind them * 3 factors: * Energy level- higher energy level is further away * Charge on nucleus- more charge pulls electrons in closer * Shielding effect- you must go through the 2nd energy level before you reach the third and so on… * Periodic Trend- going from left to right across a row the atomic size decreases. Going up and down, the atomic number increases
18. Valence electrons and be able to find charges of ions
19. Be able to draw covalent compounds (VSEPR) Bonding Domains | Atoms Around | Lone Pairs around Center | Shapes | Bond Angle | 2 | 2 | 0 | Linear | 180⁰ | 3 | 3 | 0 | Trigonal Planor | 120⁰ | | 2 | 1 | Bent |