Chemistry 1 Honors 2016 Midterm
Terms in this set (62)
Why is chemistry considered a physical science and not a biological science?
Chemistry: the study of the composition, structure, and properties of matter and the changes it undergoes
What are the branches of chemistry?
What is studied in Organic Chemistry?
the study of most carbon containing compounds
What is studied in Inorganic Chemistry?
the study of non-organic substances, many of which have organic fragments bonded to metals
What is studied in Physical Chemistry?
the study of the properties and changes of matter and their relation to energy
What is studied in Analytical Chemistry?
the identification of the components and composition of matter
What is studied in Biochemistry?
the study of substances and process occurring on living things
What is studied in Theoretical Chemistry?
the use of mathematics and computers to understand the principals behind observed chemical behavior and to design and predict the properties of new compounds
What is the difference between applied research and basic research?
BASIC Research is carried out to increase knowledge
APPLIED research is carried out to solve a problem
Requirements in order to be Matter: (two)
1. has mass
2. takes up space
What is the difference between Chemical and Physical properties?
CHEMICAL: relates to a substance's ability to undergo changes that transform it into different substances.
PHYSICAL: characteristic that can be observed or measured without changing the identity of the substance.
Be able to identify examples of Chemical and Physical properties
1. Oxygen is odorless and colorless
2. Copper turns green when exposed to the environment
3. A piece of metal is magnetic
4. The boiling point of water is 100°C
5. A gas is flammable
What is the difference between Intensive and Extensive properties?
INTENSIVE: does not depend on the
amount of matter present
EXTENSIVE: depends on the amount of matter that is
Be able to identify examples of Intensive and Extensive properties
1. Density of gold
2. Calories in a burger
3. Color of a flower
4. A block of wood has a mass of 14.2g
5. Aluminum conducts heat
What is the difference between Chemical and Physical changes?
CHEMICAL: change in which one or more substances are converted into different substances
PHYSICAL: change in a substance that does not involve a change in the identity of the substance
Be able to identify examples of Chemical and Physical changes
1. Tarnishing of silver
2. Reacting with water to form a gas
3. Supporting combustion
4. Sugar dissolving into water
5. Light is reflected off a piece of aluminum
What are the 3 states of matter and how do they relate in terms of shape and volume?
1. Solid → definite volume and definite shape
2. Liquid → definite volume but indefinite shape
3. Gas → neither definite volume nor definite shape
What are the 2 types of mixtures?
1. homogeneous (solutions) → uniform composition
2. heterogeneous → not uniform throughout
Be able to identify examples of homogeneous and heterogeneous mixtures
1. Chex Mix
2. Coffee (ready to drink)
3. Muddy Water
5. Fruit Salad
How can you tell the difference between a mixture and a pure substance? (chart on pg.15 in textbook)
MIXTURE: blend of two or more kinds of matter, each of which retains its own identity and properties ~ can be physically separated; are either homogeneous (solution) or heterogenous
PURE SUBSTANCE: has a fixed composition; are either compounds or elements
What is distinctive about Noble Gases?
they are unreactive
What are the common characteristics of metalloids?
has some characteristics of metals and some characteristics of nonmetals .
- All metalloids are solids at room temp .
- Semiconductors of electricity
- tend to be less malleable than metals but not as brittle as nonmetals
How can you tell if information in qualitative or quantitative?
qualitative = descriptive
quantitative = numerical
What are the 5 SI base units?
1. MASS: Kg
2. LENGTH: Meter
3. TIME: Second
4. AMOUNT OF A SUBSTANCE: Mole
5. TEMP: Kelvin
What is the difference between weight and mass?
Weight is a measure of the gravitational pull on matter.
Mass is a measure of the quantity of matter; it does not depend on gravity
Be able to draw the Density Triangle, definition of density and solve for the density of materials
using correct SigFigs
Density=mass/volume or D = m/v (M goes on top, D & V can go on either side of triangle)
DENSITY: the ratio of mass to volume, or mass divided by volume (kg/m^3)
Be able to calculate and round the answer to correct SigFigs. This will be used for all numeric answers.
→ Reminder for how to calcutate with Significant Figures:
Adding or Subtracting decimals,
→ the answer must have the same number of digits as there are in the measurement, having the fewest digits to the right of the decimal point.
5.432 g + 99.9 g = 105.332
3 vs 1 # after decimal so...
Answer: 105.332 g = 105.3 g
Multiplying and Dividing
→ the answer can have no more sig figs than are in the measurement, with the fewest number of significant figures.
146 m x 0.189 m = 27.594 m^2
3 vs 3 # of sig figs
Answer: 27.594 m^2 = 27.6 m^2
if it is greater than 5 → round up by 1 .
- if it is less than 5 → leave it the same .
- if it is a 5 and it is followed by any nonzero digit, round by 1.
- if it is a 5 with nothing following it, check the # in front of the 5
- if it is odd , round up by 1 .
- if it is even , leave it the same .
Be able to convert between Kelvin and Celsius temp
(know the formula)
°C + 273 = K
K - 273 = °C
How can you tell if a set of measurements are precise, accurate, both, or neither?
Accuracy → refers to the closeness of measurements to the correct or accepted value of the quantity measured.
Precision → refers to the closeness of a set of
measurements of the same quantity made in the same way.
Be able to identify what numbers in a measurement are significant figures
Tell the number of SigFigs in each:
1. 667.010 g
2. 220.0 mL
3. 0.05000 kg
4. 0.00000056 g/L
5. 0.6300 g
6. 730 cm
Be able to calculate and round the answer to correct SigFigs
round the measurement above to:
1. 4 SigFigs:
2. 6 SigFigs:
3. 1 SigFig:
Be able to convert between long form and scientific notation
using correct SigFigs:
convert → Scientific Notation
convert → standard form
5. 2.30 x 10^4
6. 1.76 x 10^-3
7. 5.40 x 10^1
8. 7.4 x 10^
1. 3.4 x 10^3
2. 2.3 x 10^-5
3. 1.01 x 10^5
4. 1 x 10^6
Be able to calculate with measurements in scientific notation
and round to correct SigFigs:
1. 200m x 300m
2. 7.8cm x 812 cm
3. (9.0 x 10^-2 cm^2) / (3.0 x 10^-1 mg)
1. 6000 = 6x10^4 m^2
2. 42000000 = 4.2x10^7 mg^2
3. 3.0 x 10^-1 cm
What law states that "a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound"?
What law states that "if two or more different compounds are composed of the same two elements , then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers"?
Be able to work examples of these
Law of Definite Proportions;
Law of Multiple Proportions
A sample of baking soda, NaHCO3, always contains 27.37% by mass of sodium, 1.20% of Hydrogen, 14.30% of carbon, and 57.14% oxygen.
Which law does this illustrate?
law of definite proportions
Nitrogen and oxygen combine to form several compounds, as shown by the following table.
Compound and Mass of N that combines w/ 1g O (g)
Which law do these data illustrate?
law of multiple proportions
What are the contributions of John Dalton?
Law of Multiple Proportions & Dalton's Atomic Theory
What are the points of Dalton's Atomic Theory?
1. All matter is composed of extremely small particles called atoms.
2. Atoms of a given element are identical in size, mass, and other properties, atoms of different elements differ in size, mass, and other properties.
3. Atoms cannot be subdivided, created, or destroyed.
4. Atoms of different elements combine in simple whole # ratios to form chemical compounds (definite)
5. In chemical reactions, atoms are combined, separated, or rearranged.
How were electrons discovered and their charge measured?
Experiments in the late 1800s showed that cathode rays were composed of negatively charged particles.
- These particles were named electrons.
- Joseph John Thomson's cathode-ray tube experiments measured the charge-to-mass ratio of an electron.
1. Who worked on the Gold Foil Experiment?
2. What happened in the experiment?
3. What were the conclusions?
1. Ernest Rutherford, and his associates Hans Geiger and Ernest Marsden
2. The scientists bombarded a thin piece of gold foil with fast-moving alpha particles, which are positively charged particles with about four times the mass of a hydrogen atom
3. results of the experiment led to the discovery of a very densely packed bundle of matter with a positive electric charge called the Nucleus.
What are they?
How to determine:
1. atomic number
2. mass number
3. number of protons, neutrons and electrons
Isotopes: atoms of the same element that have different masses
How to determine:
Mass Number = protons - neutrons
Nuclear Symbol = Mass number over atomic number + Element Symbol
Hyphen Notation = element symbol (or name) - mass number
Know how to convert b/w moles, atoms, and grams of an element
(don't forget SigFigs):
the chart will be on the test
1. You are massing a 24K gold chain, and find that it weighs 400grams. Determine how many moles of gold you have.
2. Calculate the mass in grams of 0.0450 moles of chromium.
3. A silicon chip has a mass of 0.006g. How many silicon atoms are present in the chip?
4. Find the mass in grams of 1.00 x 10^23 atoms of Nitrogen
molar mass = the atomic mass from the periodic chart
1. 400g Au - 1 mol Au
------------ 196.97 g Au
= 2.030766... =
2 mol Au
2. 0.0450 mol Cr - 52.00 g Cr
-------------------- 1 mol Cr
2.34 g Cr
3. 0.006 g Si - 1 mol Si - 6.022x10^23 atoms Si
-------------- 28.09 g Si ----- 1 mol Si
= 1.286... =
1 x 10^20 atoms Si
4. 1.00x10^23 atoms N - 1 mol N - 14.01 g N
---------------- 6.022x10^23 atoms N - 1 mol N
= 2.326... =
2.33 g N
How does frequency, wavelength, and speed of a wave relate?
c = λν
c = speed of light
λ = wavelength
ν = frequency
What causes a line emission spectrum to be formed?
When the emitted light/color photon is seen through a prism
What is the difference in ground state and excited state of an atom and how does an atom move b/w these two states?
Atoms normally exist in their ground state, where energy is minimal. There is only one ground state for an atom. Atoms absorb energy and go into excited state where energy is higher. There are many levels of excited state.
How was Bohr's model of the atom different from previous models?
- Bohr knew the mistakes of Rutherford's model and the new information about electrons and their dual wave-particle nature.
- He tried to better Rutherford's model that had no electron organization and put the electrons in specific orbits, represented as concentric circles, around the nucleus.
- Using electron orbits, Bohr was able to explain the emission-line spectrum of hydrogen and its one electron.(downfall was that it only worked for hydrogen)
What information can be gained from each of the four quantum numbers?
1. Principle Quantum Number: indicates what energy level the electron is in
2. Angular Momentum Quantum Number: indicates what sublevel, inside the energy level, the electron is in.
3. Magnetic Quantum Number: Tells how many orbitals are in the sublevel and gives their orientation
4. Spin Quantum Number: Pauli exclusion principle; 2 options → clockwise and counterclockwise → +½ & - ½
Given an electron configuration notation, how can you determine the element? examples:
1. 1s^2 2s^2 2p^1
2. 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^1
use the last exponent and letter
1. Boron (1st element in 2p)
2. Rubidium (1st element in 5s)
How can you tell how many sub-levels are in an energy level?
Angular Momentum Quantum Number;
- s = 1
- p = 2
- d = 3
- f = 4
(last letter used in notation)
How can you tell how many orbitals are in each sub-level?
Magnetic Quantum Number;
- s = 1
- p = 3
- d = 5
- f = 7
Maximum 2 electrons per orbital.
How did Moseley change Mendeleev's periodic table?
Henry Moseley discovered that the elements fit into patterns better when they were arranged according to atomic number, rather than atomic weight.
- Modern Periodic Law: The Periodic Law states that the physical and chemical properties of
the elements are periodic functions of their atomic numbers.
Given a noble gas configuration, how can you locate the element on the periodic table? examples:
1. [Ne] 3s^2
2. [Rn] 7s^2 5f^10
use the last exponent and letter
1. Magnesium (2nd element in 3s)
2. Californium (10th element in 5f)
How was Mendeleev's periodic table different from those before it?
Mendeleev noticed that when the elements were arranged in order of increasing atomic mass, certain similarities in their chemical properties appeared at regular intervals.
Mendeleev created a table in which
elements with similar properties were
How is fluorine's electronegativity different from other elements?
it is the most electronegative element
- electronegativity trends are caused by the movement closer or further away from Fluorine
What is the difference between electron affinity and ionization energy?
ELECTRON AFFINITY: the energy change that occurs when an electron is acquired by a neutral atom
IONIZATION ENERGY: the energy required to remove one electron from a neutral atom of an element
Why is it better for atoms to be bonded to other atom(s) instead of being independent?
Because it makes their potential energy lower when compared to independent atoms
What is the difference b/w covalent, ionic, and metallic bonds?
- require at least 1 cation and 1 anion (illustrated by dot notations)
- external bond
- b/w 2 atoms sharing electron pairs
- occur in materials that are 100% metallic (elements involved must be metals)
- sea of electrons
What are the 2 types of covalent bonds and how are they different?
POLAR: unequal sharing &NON-POLAR: equal sharing
What is the difference between a molecule and a formula unit?
covalent bonds form molecules
ionic bonds form formula units
Define Octet Rule
Chemical compounds tend to form so that each atom, by gaining, losing, or sharing electrons, has an octet of electrons in its highest occupied energy level
Be able to identify correct lewis structures
Reminder for how to form a Lewis Structure:
1. draw a dot notation for every element in the compound
2. put the element with the most bonding sites (single dots) in the middle
3. add the other elements around the central one. It's okay to rotate the location of the dots, just don't change the number of dots
4. add multiples of the elements as needed until all elements have a full dot notation → 8 dots (H has 2)
What is the strongest/weakest type of intermolecularforce?
→ hydrogen bonding
→ London dispersion forces