Chemistry Mid-Term Exam
1.Define Organic Chemistry (study of things that contain carbon. there are more of these than inorganic compounds), Inorganic Chemistry (study of things that don’t contain carbon), Physical Chemistry (study of energy formed by a chemical reaction), Analytical chemistry (study of the composition of different kinds of matter), Biochemistry (study of the chemistry of living things).
2.Why are there more organic than inorganic compounds known to chemistry? b/c there are more compounds that contain carbon than don’t.
3.Define Matter (something that has mass and volume), mass (how much something there is usually measured by weighing), volume (how much space something takes up).
4.What does SI mean? System International
How does the metric system relate to SI? SI is based on the metric system.
SI unit– volume liter
SI unit-mass kilogram
SI unit– length meter
metric unit– mass kilogram metric unit-length meter
5.What are the three states of matter? Solid liquid, gas.
Which of the 3 states of matter are compressible, have definite shape, and definite volume?
solid– def shape, mass, and volume- incompressible
liquid- def mass and volume- compressible
gas- def mass- compressible
6.What is vapor? Gas from a substance that is normally a liquid or solid at room temperature.
7.What is a substance? definite composition, element, or compound, can be mixture.
8.What is catalyst? Something that speeds up a chemical reaction, never chance or used up.
9.What is an element? simplest form of matter with unique properties.
10.What is the difference between a mixture and a compound? Mixtures are separated by physical changes and compounds are separated by chemical changes.
Homogenous mixture- also call a solution: same composition everywhere, one part is the same as any other part.
Heterogenous mixture- not the same composition all the way through, some parts are different.
11.What does aqueous mean? means water, solution: dissolved in water.
12.What does inert mean? Non-reactive
13.What is a precipitate? solid which forms out of a liquid.
14.Define Chemical Change (atoms are rearranged, combinations of matter change), Physical Change (changes you can sense, can be measured and do not change the combinations of atoms), Physical Property (can be sensed, measured without changing the combination of matter), Chemical Property (how a certain type of matter behaves with other types of matter).
a.distillation separates things by physical changes
b.Mixtures can be separated by physical changes while compounds can be separated by chemical changes
15.Where are the reactants and products in a problem? Reactants (left) Products (right)
16.Define intensive property (Depends on what something is made of), extensive property (depends on how much of something there is).
17.What is Density? mass divided by volume (m/v)
a.When we compare density, volume stays the same, and mass changes
b.What is specific gravity? How do you get it from g/cm3? What is tells us? Why we use it?
18.In consumer products: ingredients are listed in what order? Greatest amount to least. When comparing pharmaceutical and health products you should compare inert or active ingredients? Active
19.What does conservative mean in Chemistry? the preservation and careful management of the environment and of natural resources
20.What is Lavoisier’s Law of Conservation of Mass and Matter? matter can’t be created or destroyed even though things sometimes seem to disappear in a chem. reaction all atoms are there, always finish with what you start with
21.Quantitative- give results with numbers and units, Qualitative- describe with a nonnumeric form
22.Precision- how close several measurements is to a true value, accuracy- how close a single measurement is to a true value.
23.Know significant figure and what they tell you.
24.1 ml= 1 cm3
25.Deci- 1/10, centi- 1/100, milli- 1/1000, kilo- 1000, mega- 1000000.
Freeze | Boil | |
F⁰ | 32⁰ | 212⁰ |
C⁰ | 0⁰ | 100⁰ |
K | 273k | 373k |
26.Temperature the measure of? How fast atoms vibrate
a.Where does water freeze and boil in F⁰, C⁰, and K.
b.What happens in absolute zero? Matter stops vibrating.
c.Why does the k scale start here? It needs to start where
There is no movement.
27.Who discovered the Law of Definite Proportions? Proust, a specific substance always has the same proportion of elements by mass. Water is always 94% O by 6% H mass.
28.What did Thompson’s experiment with a cathode ray tube show about the particle that make up an atom? they’re negatively charged particles called electrons.
29.What did Rutherford’s experiment tell us about the nucleus? It tells us that the nucleus is very dense.
30.If a nucleus of an atom were the size of a golf ball the nearest electron would be how far away? 1 mile
31.Mass (in amu)? 4 amu. Charge of protons? +1, Neutrons? 0, Electrons? -1.
32.What does an atomic number tell you? It tells you how many protons and electrons are in the element
What does a mass number tell you? Sum of protons and neutrons
What does an atomic mass tell you? Average sum of the element (the average atomic mass)
Where is an atomic number on the periodic table? Top right corner, above element symbol
Where can you find the mass number? add protons and neutrons or in isotope name
Where is the atomic mass on the periodic table? Underneath the element symbol.
33.What is an isotope? atoms in the same element with different number of neutrons
34.What does the isotope name strontium- 90 tell you? strontium atom mass#= 90 (so p +n = 90)
35.What does the strong force do? It keeps the protons and the neutrons together in the nucleus.
Why is the strong force so strong? It is so strong because it keeps the nucleus together and the protons repel each other making it strong.
a.What limitation in the strong force makes atoms unstable? It works over a small distance
36.Why atomic nuclei are most stable when p=n and atomic # <82? nature like p+=n°, once p+= 82 or over, it becomes too big for nucleus
37.What the line/curve of stability is and how beta loss or gain changes an element in relation to the curve of stability?
38.What is transmutation? When one element turns into another element
39.What is radioactive decay? when the nucleus loses pieces to become stable.
40.What is radioactivity? the process of pieces of the nucleus flying out and giving off radiation
What are the four types of radioactivity? alpha, beta, gamma rays, neutron
41.Define Fission (slow neutron hits a nucleus, nucleus splits in 2), Fusion (2 small atoms crush together to make one big one).
a.Biggest problem with fission as a source of energy is nuclear waste, Why do reactor have to be refueled? all the uranium splits eventually, so you have to refuel it to do fission again.
b.The biggest problem with fusion as a source of energy? you have to put more energy in than you get out.
c.Where has a modern facility been built to store nuclear waste? Yucca mountain, Nevada
42.What do control rods do in a nuclear reactor? push in/ pull out neutrons
43.What is a chain reaction is in fission, where it is used? The more n° flying around split more atoms and cause more decay.
44.What is a half-life? time for 1/2 mass of isotope to change into something else
45.The father of the periodic table is? Mendeleev
46.The Periodic Law states? if elements in order of increasing atomic number, chemical properties will be periodic
47.rows on the periodic table are called periods. Columns on the periodic table are called groups.
48.The octet rule is? atoms will lose, gain, or share e- to get 8 in their outer energy level
49.What is the oxidation number of an element? charge it has when it fulfills the octet rule
ex. K (+1), O (-2), F(-1)
50.4s2p3 is the electron configuration for (As)
51.Define metal (good conductors of heat and electric current; left of the staircase), transition metals (unpredictable; in the valley), representative metals (predictable; mountains).
52.metalloids have properties of both metals and nonmetals.
53.how atomic size and electronegativity change as you go across or down the periodic table and why? across: pull e- more because nucleus force stronger down: pull e- less because nucleus force weaker.
54.What is a cation (ion with + charge), anion (ion with – charge)
How is a cation formed? lose e-
How is an anion formed? gain e-
55.What is a ionic bond (between metal and nonmetal, stick together in big blob, form crystalline structure), covalent (between 2 nonmetals, form individual molecules)
What elements are likely to form an ionic bond? Metals and nonmetals Covalent Bond? 2 nonmetals
56.What is a metallic bond? in a piece of metal, the metal atoms hold valence e- so weakly that they float between atoms
57.Van der Waals? between molecules, very weak, e- not shared equally spend more time with one element than others that side is – and side where less time spent is +.
58.Allotropes? same substance with different crystalline structure.
59.Crystalline Structure? particles, atoms, ions, or molecules arrange themselves in a repeating pattern.
60.Formula unit? ratio of anions to cations in ionic bond in lowest terms
Molecular formula? how many atoms in each molecule
61.How atoms are bonded and physical characteristics of ionic and covalent compounds?
Physical Properties of Ionic bonds? Usually hard crystals, brittle, solid, conducts electricity if dissolved in water, high melting or boiling point. Physical Properties of Covalent Bonds? Can be solids, but lots of liquids and gasses, low melting and boiling point
62.Know how to name ionic and molecular compounds