What are the base units for scientific measurements?
g, m, l
Convert the following units.
21.7 cm -> .217 m
1.18 km -> 1180 m
2.23 mL -> .00223 L
35.2 mL -> 35.2 cm3
How many significant figures are in the following numbers.
414.76 m 5 sig fig
1.0001 km 5 sig fig
Calculate the following with correct sig figs.
2.215 cm X 1.1 cm 2.4 (lowest sig fig was 2, so answer can only have 2)
Calculating the densities D=m/v
54 g, 1.4 cm X 4.2 cm X 2.2 cm
54 g/13 cm3 = 4.2g/cm3
23.3 g, 35.6 mL
23.3 g/35.6 mL = .654 g/ml
Rewrite in scientific notation.
1,202,000,000
.0000007080
12,676,230
.000016
1.202 x 109
7.080 x 10-7
1.267623 x 107
1.6 x 10-5
Name the parts of an atom, their locations, and their charges
Proton, 1 amu, +1 charge, nucleus
Neutron, 1 amu, no charge, nucleus
Electron, 1/2000 amu, -1 charge, around atom
Find the atomic number, mass number, # protons, neutrons, and electrons for Neon – 23.
Atomic # - 10, mass # - 23, protons – 10, neutrons – 13, electrons – 10.
Define isotope
An isotope is an atom that has a differing atomic mass due to different numbers of neutrons. Written as Carbon-14
or C14
Find how many moles and # molecules in 51.9 g NaCl.
51.9 g NaCl (1 mol NaCl/58.44 g NaCl) = .89 mol NaCl
.89 mol NaCl (6.022x1023 molecules/1 mol NaCl) = 5.35 x 1023 molecules NaCl
Name and explain the three phases of property.
Solid – definite shape & volume, atoms are closely packed and can not move around much
Liquid – definite volume / no shape, atoms are loosely packed and can move around each other
Gas – no shape or volume, atoms are far apart and can easily move around
Describe both chemical and physical changes. Be able to distinguish both.
Physical change – change in appearance without changing chemical make-up of material
Chemical change – change in the chemical nature, not the same material that you start with.
Explain the laws of conservation of matter and energy.
Matter/energy can neither be created nor destroyed.
Contrast accuracy and precision.
Accuracy focuses on how close to the true value a measurement is while precision focuses on the ability to repeat
the same measurement.
Compare and contrast qualitative and quantitative observations.
Both are observing. Qualitative bases on how it looks. Quantitative looks at measurements & values.
Explain the work of Dalton, Rutherford, and Bohr.
Dalton – 1) atoms are indivisible, 2) all atoms of the same element are the same, 3) atoms of different elements are
different, 4) atoms of different elements combine to form compounds, 5) reactions are the rearrangement of atoms
in molecules
Rutherford – found the nucleus, rest of atom is “empty space”
Bohr – developed idea of orbits or energy levels for electrons
Explain nuclear instability and radioactive decay.
When the ratio of protons to neutrons strays two far from balanced, the nucleus becomes unstable and will break
apart in an attempt to get back into balance. A stable ratio will be between 1P:1N and 1P:1.5N (ie. Magnesium
would be stable between 12P:12N and 12P:18N, either side would not be stable
What keeps the protons and neutrons together in the nucleus
Strong forces attract particles when they are extremely close and are strong enough to overcome the repulsion of
the positive protons
Valence electrons – what they are and how to determine how many an atom has
Valence electrons are the electrons in the outer energy level. They are the last set of electrons in an electron
configuration. They can also be found by counting the family the element is in and that tells the # of valence
electrons (skipping transition metals).
What do the quantum numbers s, p, d, and f refer to and how many electrons can each hold?
s,p,d and f are orbitals. S holds 2 electrons, p holds 6 electrons, d holds 10 electrons, f holds 14 electrons.
Explain Aufbau’s principle, Hund’s rule, and the Pauli Exclusion principle.
Aufbau – energy levels with lowest amounts of energy are filled before electrons are put in higher energy levels
Pauli – no two electrons can have the same 4 quantum numbers; therefore, each individual orbital must have one
electron with a positive spin and one of a negative spin.
Hund – when filling an orbital, one electron with the same spin must be placed in each orbital before a second
electron can be added to any orbital
What is the relationship between wavelength, frequency, energy, and light color.
Increase frequency = increase energy
Increase frequency = decrease wavelength
High frequency = blue, low frequency = red
Electron Configurations – what they are and be able to draw some for main group and transition metals
Keep track of where electrons are – draw with arrows (we can find orbital notation – below – from the electron
configuration)
Mg – 1s22s2p63s2
Se – 1s22s2p63s2p6d104s2p4
Be able to write Orbital Notation and Noble Gas Notation for atoms through Krypton. Do 2 from each period.
Where are the following families of the periodic table – Alkali, Alkali Earth, Halogen, Noble Gases, Main Group,
Transition Metals?
Alkali – 1
Alkali Earth – 2
Halogen – 7 or 17
Noble Gases – 8 or 18
Main Group 1&2 13-18
Transition Metals – 3-12
Determine the orbital notation for the following atoms
Mg
1s22s2p63s2
Cu
1s22s2p63s2p6d9
Br
1s22s2p63s2p6d104s2p5
Where are the S, P, D, and F block elements
S – 1&2
P – 13-18
D – 3-12
F – lanthanide & actinide series
Definitions of Effective Nuclear Charge, Ionization Energy, Electron Affinity, and Electronegativity.
ENC – pull on valence e by nucleus ~ the number of valence e
Ionization energy – energy needed to remove an electron
Electron Affinity – change in energy as an atom gains an electron
Electronegativity – the ability of an atom to pull an electron from another atom
Relationship between Effective Nuclear Charge and the following – atomic radii, ionic radii, ionization energy, electron
affinity
As ENC increases, Ionization energy, Electron Affinity, and Electronegativity increase; size decreases
Ionic size depends on the gain or loss of electrons and how many are gained or lost
Trends in the periodic table in relation to Effective Nuclear Charge, Ionization Energy, Electron Affinity, and
Electronegativity.
Moving across the table, ENC increases.
Moving down a family, ENC decreases.
As ENC increases, so does IE, EA, and EN, size decreases.
Bond types- explain them, types of elements involved, what electrons are doing in each, how to determine (element types
and electronegativities)
Metallic bonds – only metals, share electrons everywhere – “sea of electrons”
Ionic – metal & non-metal, difference in electronegativities of 1.7 or more, electrons are transferred from one atom
(metal) to the other ( non-metal) making opposite ions which are attracted to each other
Polar covalent – two non-metals, electrons are shared but not evenly, electronegativity difference of .4 to 1.6.
Nonpolar covalend – two non-metals share electrons evenly, electronegativity difference of .3 or less
What is the bond length and energy relationship
As bond length decreases, bond energy increases
Explain the octet rule and how it is met with bonds
Atoms want an octet of electrons in the valence shell. Gaining/losing or sharing electrons enables atoms to reach
the octet.
Explain Resonance structures
Molecules may have more than one way to draw the lewis structure, and a resonance structure shows this.
Ozone O=O-O <-> O-O=O
Draw electron dot diagrams and find lewis structures for the following compounds
CH2O
PH3
SiO2
SiH4
SCl2
Explain why CO2 is not a polar molecule, but H2O is even though both have polar bonds. (hint – look at the shape)
Explain dipole-dipole forces, london dispersion forces, and hydrogen bonds. Tell what phase each is most likely to be.
Impacts of bond types on characteristics – melting point, solubility, conductivity
Melting points (highest to lowest) – metallic, ionic, hydrogen bonds, dipole-dipole forces, London dispersion forces
Ionic are soluble, will conduct electricity in water
Metals are not soluble, will conduct electricity as a solid
Polar covalent may be soluble, will usually not conduct electricity in water
Non-polar covalent– not soluble or conductive
Naming compounds, polyatomic ions, and acids
Know the polyatomic ions so you can name and write formulas
Acids – ate becomes ic, ite becomes ous
Find the % composition of Mg(NO3)2
Mg
24.31 g / 148.33 g = 16.39%
N
28.02 g / 148.33 g = 18.89%
O
96.00 g / 148.33 g = 64.72%
Total mass = 148.33 g
Find the correct chemical formula if it has a molar mass of 56.12 g/mol, and is 86% Carbon and 14% Hydrogen.
86 g C (1 mol C/12.01 g C) = 7.16 / 7.16 = 1 mol C
14 g H (1 mol H/1.01 g H) = 13.86 / 7.16 = 1.94 mol H -> 2 mol H
Empirical formula = CH2, Empirical mass = 14.03 g
Molecular mass is 4 times the empirical mass, so the molecular formula is 4 times the empirical formula
Molecular formula is C4H8
Draw, name, and write the formula for 6 organic molecules, including some double and triple bonds.
Variety of samples – see reviews and quiz
Write the molecular formula for each of your organic molecules above.
Write the isotope for a neutral oxygen atom with 7 neutrons in both isotope formats.
8 P, 7 N, so mass number is 15
Oxygen-15
15
8O
The half-life of Barium-139 is 86 minutes. How long would it take for a 8 g sample to decay to less than 0.1 g?
1st half-life
4g
2nd half-life
2g
3rd half-life
1g
4th half-life
0.5 g
th
5 half-life
0.25 g
6th half-life
0.125 g
7th half-life
0.0625 g
7 half lifes = 602 minutes
Be able to identify the following tools – beaker tongs, crucible tongs, ring, triangle, crucible & lid, mortar & pestle,
Erlenmeyer flask, test tube holder, test tube clamp, buret, pipet (both graduated & volumetric), wire gauze