Chemistry FINAL!!!!! Flashcards
Mulipying and dividing Sigfigs
Do not round until the end
Count number of sigfigs in each number
Find the number with the lowest amount of sigfigs.
Sigfig rules
All non zero digits are significant.
Zeros between sigfigs are significant. EX (0.504)
Leading zeros are not significant
Trailing zeros after a decimal place are significant EX.(4.0)
97(2) and 97.00(4) are different
Trailing zeros can be significant, if a deciaml is shown.
Exact numbers have an infinite amount of sigfigs.
All digits that compromis “n” are significant Ex. (10^x is not significant).
Adding and subtracting sigfigs
Do not round until the end
Find number with least amount of decimal places.
Density equation
Density = Mass divided by volume
Physical property
Characteristic of a substance that can be observed without changing it to something else.
Chemical property
Characteristic of a substance that can only be observed if it is changing
Extensive property
Change based on how much matter we have
Ex. Volume, shape, mass
Intensive property
Stays the same no matter how much matter we have
Ex. Color,texture, boiling/freezing point, density
Mixture
Made of two or more pure substances
Element
Substances that cannot be seperated into simpler substances by chemical means
Compound
A pure substance composed of two or more elements whose composition is constant
Law of definite proportions
A pure substance will contain same elements in same proportions by mass
Alloy
- Made of two or more metals, or a metal and a nonmetal (must be solid at room temp)
- Melt solid components and allow to mix/dissolve
- To identify must know types of metal/solid used.
Subscript
Say how many atoms of a certain element are present
If there are no subscripts then there is only 1 atom of that element.
Coefficient
Determines how many is needed
_ c2h4 + 3 o2 –> 2co2 + 2h20
c = 2
h = 4
0 = 6
Law of conservation of matter/mass
Matter cannot be created or destroyed
During chemical reactions, no matter is lost/gained
Elements you start with, you end with
Physical changes
Type of matter that has not changed
* mas, shape, volume, state of matter
Change is often reversible
*phase change, shape
Chemical changes
Type of matter that has changed into another matter
Change is often not reversible
* combustion
Generally, if the observalbe intensive properties have changed, then a chemical change has occured.
Reactants
Chemicals you start with
* CH4 + 02 —->
[________]
Reactants
Synthesis equation
A+B ——> AB
Decomposition equation
AB —–> A + B
Single replacement equation
AB + C ——> BC + A
Double replacement equation
AB + CD —–> AD + CB
Combustion equation
C x Hy + o2 —-> CO2 + H2O
Synthesis identification
Count reactants and products, start with 2, end with 1
Decomposition identification
Count reactants and products, start with 1, end with 2
Single replacement identification
You will have a pure element on BOTH sides of the equation
Double replacement identification
Second element of each compound swap
Combustion identification
A hydrocarbon oxygen gas are always the reactants because h2O is always a product
Know how they drew the atom Jj thompson
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Know how they drew the atom Erwin shrodinger
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Know how they drew the atomLouis Debrogile
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Know how they drew the atom Bohr
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Know how they drew the atom John Dalton
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know how the drew the atom Democritus
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Robert milikan
Oil drop
* discovered mass/ change of electron
*change: 159 ^ 10-19
*Mass: 9.13 ^10-31 kg
Cathode tube ray experiment discovery
An electron is a subatomic particle that is found in all atoms, is negatively charged, and has extremely small mass (200 * lighter than a hydrogen atom).
Alpha particles
2 protons, 2 nuetrons
Mass number: 4 amu
Charge: +2
Beta particles
Electrons
Mass number: 0
Charge: -1
Gamma radiation
High energy proton with short wavelengths
Mass number: 0
Charge: 0
Alpha decay
233 -4 229 4
NP ———> PA + He
93 -2 91 2
Beta decay
40 0 40 0
K —–> Ca e-
19 +1 20 -1
Valence electrons
-Found in the highest energy level of an atom
- Responsible for bonding properties of an atom
Rule 1 for lewis dot structure
Write element symbol
Rule 2 for lewis dot structure
Figure out how many valence electrons you need
Rule 3 for lewis dot structure
Draw dots to represent electrons along the symbol
Draw on “4 sides”, order does not matter
Every side needs 1 electron before pairs
Wavelength
Distance between 2 adjacent crests or troughs
Frequency
Number of waves that pass through a given point per second
Photoelcetric effect
WHen a metallic surface is exposed to radiation of a certain frequency, electrons can be emitted
Electron configuration
Shows an arrangement of electrons in an atoms and shows how electrons are distributed in orbital
Lavoisier
Made first list of 33 elements
J.W. Dobereiner
Arranged known elements into triads
John newlands
Arranged by increasing atomic mass
Mendeleev and Lothar meyer
- Ordered 63 elements by increasing atomic mass
- Left space for unknown elements
Moseley
Organized by atomic number instead of mass
