Unit 1: Matter & Measurement 1. Substance : a. Homogeneous matter b. ONLY ELEMENTS & COMPOUNDS ARE SUBSTANCES 2. Element: a. Atoms of a single type b. CANNOT be broken down by a chemical change c. Particle diagrams: element-Ca elemet-N 2 3. Compound: a. Substances made of 2 or more elements chemically combined in a definite proportion b. Composition is fixed (homogeneous composition) c. CAN be broken down by a chemical change d. Can be represented by specific formulas e. Particle diagram: 4. Mixture : 2 or more distinct substances physically combined a. General properties i. Composition can vary ii. Retains the properties of their components iii. Separation methods: 1. Magnet – can take iron out of a mixture 2. Distillation – used to separate substances with different boiling points & molecular polarities 3. Filtration – used to take an INSOLUBLE substance out of a mixture 4. Chromatography – used to separate different sized molecules in a mixture 5. Centrifuge – used to separate substances by density b. Types of Mixtures: i. Homogeneous-uniform composition 1. solution that is "completely dissolved " ii. Heterogeneous-non-uniform composition compound-H 2 O
33
Embed
Unit 1: Matter & Measurementwebutuckchemistry.weebly.com/.../1/1/25111863/review_sheet-units_… · Unit 1: Matter & Measurement 1. Substance: a. ... General properties i. ... 10.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Unit 1: Matter & Measurement
1. Substance:
a. Homogeneous matter
b. ONLY ELEMENTS & COMPOUNDS ARE SUBSTANCES
2. Element:
a. Atoms of a single type
b. CANNOT be broken down by a chemical change c. Particle diagrams:
element-Ca
elemet-N2
3. Compound:
a. Substances made of 2 or more elements chemically combined in a definite proportion
b. Composition is fixed (homogeneous composition)
c. CAN be broken down by a chemical change
d. Can be represented by specific formulas
e. Particle diagram:
4. Mixture: 2 or more distinct substances physically combined
a. General properties
i. Composition can vary
ii. Retains the properties of their components
iii. Separation methods:
1. Magnet – can take iron out of a mixture
2. Distillation – used to separate substances with different boiling points &
molecular polarities
3. Filtration – used to take an INSOLUBLE substance out of a mixture
4. Chromatography – used to separate different sized molecules in a mixture
5. Centrifuge – used to separate substances by density
b. Types of Mixtures:
i. Homogeneous-uniform composition
1. solution that is "completely dissolved"
ii. Heterogeneous-non-uniform composition
compound-H2O
c. Particle diagrams:
Heterogeneous
mixtures
Homogeneous
mixtures
element -compound
element-compound
element-element
element-element
compound-compound compound-compound
5. Physical Changes: DO NOT result in the formation of a new substance; can be either reversible or
irreversible
a. Examples:
i. Phase change (reversible)
1. Evaporation/Condensation
2. Melting/Freezing
3. Sublimation/Deposition
ii. Dissolving (reversible)
iii. Cutting into smaller pieces (irreversible)
6. Physical Properties: are constant & do not change
a. Examples:
i. Color
ii. Odor
iii. Solubility
iv. Melting Point/Boiling Point
v. Hardness
vi. Conductivity
vii. Phase
viii. Density-Table T
1. in a given volume the greater the number of atoms, the greater the density does
not result in the forming of a new substance
7. Chemical Changes: results in the formation of a new substance & indicated by the words "reacts",
"forms", "combines"
a. Chemical changes are independent of the amount of the substance
i. 300 kg Al2O3 & 400 kg Al2O3 have the same chemical properties
b. Examples:
i. Electrolysis
ii. Rust
iii. Combustion
8. Chemical Properties: behaviors exhibited when substances react
a. Examples:
i. Combustibility
ii. Reactivity
iii. Reaction rate
iv. Ability to oxidize
v. Ability to rust
vi. Reacts with acids/bases
9. Phases of Matter
Solid Liquid Gas
Definite shape & volume, particles
vibrate
No definite shape, definite volume,
particles vibrate & rotate
No definite shape or volume,
particles vibrate, rotate, translate
10. Density
1. calculating volume
a. regular solid=l x w x h
b. irregular solid=displacement method object is put into water
i. volume(object)=v(final)-v(initial) Example: What is the density of a substance with a mass of 900 grams and a volume of 30cm
3? Units:
volumeL, mL, cm3
massg, kg
densityg/mL, g/ cm3
d = 900 = 30 g/cm3
30
* Densities of elements can be found on Table S!
d = m
V (Table T)
11. Percent Error (Table T)
% error=(measured-accepted) x 100
accepted
measured=experimental=determined
accepted=standard=expected=actual
12. TERMS
(s)=solid
(l)=liquid
(g)=gas
(aq)=aqueous refers to a substance in water & therefore is ALWAYS a mixture
Unit 2: Atomic Structure
1. Models
a. Dalton: Hard Sphere
i. All elements made of atoms. Atoms of one element are alike, but different from atoms of
different elements.
b. Thomson: Plum Pudding
ii. electrons have negative charge
c. Rutherford: Gold Foil Experiment
iii. atoms are mostly empty space, nucleus is dense and positively charged
d. Bohr: Planetary Model
iv. electrons are in fixed orbits around nucleus
e. Modern: Wave Mechanical Model (Electron Cloud)
i. Protons & neutrons in nucleus
ii. Electrons in orbitals around nucleus
1. orbitals: areas of high probability where electrons will most likely be found
2. Atom: a. positively charged nucleus surrounded by negatively charged electrons
b. electrically neutral: the number of protons=the number of electrons; (p=e-)
c. subatomic particle:
i. proton
1. the mass of a proton is 1 amu (1 u) & has approx. the same mass as a neutron; the
charge is +1
2. number of protons in an atom is used to identify the element
ii. neutron
1. the mass of a neutron is 1 amu (1 u) & has approx. the same mass as a proton; the
charge is 0
iii. electron (also called a beta particle)
1. the mass of an electron is 1/1836 amu (1/1836 u); the charge is -1
See Table O for symbols
Proton Neutron Electron
Charge +1 0 -1
Mass 1 amu 1 amu 1/1836 amu
Location nucleus nucleus Orbitals/electron
cloud
3. Isotopes:
a. Have the same atomic # (same # of protons) but different mass #s BECAUSE THEY HAVE
DIFFERENT NUMBERS OF NEUTRONS b. have the SAME BRIGHT-LINE SPECTRUM because they are the SAME ELEMENT
i. the isotope that is more abundant will have an atomic mass closer to the atomic mass
listed on the periodic table
ii. Example 1:
a. Boron-10 & Boron-11; since atomic mass of Boron (B) is 10.81, Boron 11
is more abundant
iii. Example 2: H-1, H-2, H-3 (the number indicates the mass #)
4. Atomic Mass (average atomic mass): weighted average mass of the naturally occurring isotopes of an
element
a. Example: The isotopes of chlorine are Cl-35 and Cl-37. In nature 75 % of all Cl atoms have a
mass of 35 amu (Cl-35) and 25 % of all Cl atoms have a mass of 37 amu (Cl-37). Calculate the
average atomic mass of Cl.
M.A.D. = Multiply (the % by the given mass # for each isotope)
Add (the answers from the multiplication problems)
Divide (the sum by 100)
(35 x 75) + (37 x 25)
100
5. Ground State/Excited State a. Bright-Line Spectrum: produced when electrons move from higher energy states to lower energy
states releasing energy in the form of light
i. excited state-when an electron gains enough energy to move from a lower energy level to
a higher energy level
ii. ground state-lowest energy configuration (listed on the periodic table as the electron
configuration)
6. Electron Dots (Lewis Structures) a. Used to show the number of valence electrons an element has
1 2
8 3
5 6
7 4
7. Notation
a. isotopic 235
U
b. argon-40 (40 is the atomic mass)
X
94
Unit 3: Periodic Table
1.
A. Periods go across. Elements in the same period have the same # of principal energy levels (PELs)
B. Groups go down. Also called families. Families of elements share similar chemical properties because
each element in a family has the same # of valence electrons.
2. Metals: to the left of the zig zag line
1. Most active metal: Fr (bottom left)
2. Metals have low ionization energies, low electronegativities, lose electrons, form positive ions, are good
conductors, are malleable & ductile, most are solid (mercury Hg is the only liquid).
3. Nonmetals: to the right of the zig zag line
1. Most active nonmetal: F (top right, group 17, not 18)
2. Nonmetals have high ionization energies, high electronegativities, gain electrons, form negative ions
with metals, share electrons with nonmetals, lack luster, are brittle, are poor conductors, can be solid,
liquid (bromine), or gas (H, He, N, O, F, Cl, group 18)
4. Metalloids: touch the zig zag line (not Al, though)
1. Have some properties of both metals and nonmetals
5. Noble Gases: Group 18
1. Monatomic gases that don’t usually react with other elements. Kr & Xe can form compounds with F or
O.
2. Have complete valence PEL = stable configuration, stable octet
3. Have dispersion forces between molecules (weak forces of attraction). Dispersion forces increase with
larger mass so boiling point of Kr is higher than He.
6. Ions: do not have equal number protons & electrons & therefore they have a charge.
+ ions = less electrons than protons
- ions = more electrons than protons
7. Allotropes: forms of the same element that have different molecular formulas.
1. Ex: carbon can be in many forms, coal, diamond, graphite, buckminsterfullerene.
a. In all forms, atoms are arranged differently, which leads to different physical & chemical
properties.
8. Properties of Substances
Physical Chemical
Color, odor, solubility, MP, BP, hardness,
conductivity, phase, density
Things you can observe without changing the
substance into something else
Combustibility, reactivity, reaction rate
Things that describe how an element behaves in a
chemical reaction
9. Groups:
1. Elements in the same group react similarly because they have the same # of valence electrons.
2. Down a group
a. radius increases due to an increase in the # of PELs.
b. Electronegativity and ionization energy decrease down a group b/c the valence electrons are
farther away from the nucleus.
c. For metals, activity increases down a group because the electrons become more shielded by inner
PELs, making it harder to hold onto the valence electrons.
3. Group 1: alkali metals = most active metals, form +1 ions, lose electrons easiest
4. Group 2: alkaline earth metals = very active metals, form +2 ions
5. Transition metals: groups 3-12: make solutions with colorful ions
6. Group 17: halogens = most active nonmetals (gain electrons easiest)
7. Group 18: noble gases = mostly inactive, stable electron configurations
10. Periods:
1. as you go across a period (LR)
a. atomic radius generally decreases
b. electronegativity and ionization energy increase across a period due to increase in nuclear
charge.
c. More positive protons in the nucleus mean a tighter hold on the negative electrons.
11. Ionization Energy: amount of energy required to remove an atom’s most loosely held electron.
1. Lower IE, easier to take away an electron.
2. IE decreases down a group & increases across a period.
12. Electronegativity: attraction of a nucleus for electrons.
1. Higher electronegativity, tighter hold on e-.
2. Electronegativity decreases down a group & increases across a period.
13. Atomic Radius: half the distance between nuclei that are next to each other (or the distance between the
nucleus & its valence e-)
1. Radius increases down a group & decreases across a period.
14. Ionic Radius
Metals Nonmetals
Since metals lose e- to become positive ions, the ionic
radii for metals are smaller than the radii for metal
atoms
Loses electrons +
Metal atom metal
ion (+)
Since nonmetal atoms gain electrons to become ions,
the ionic radii for nonmetals are larger than the radii
for the nonmetal atoms
Gains electrons Nonmetal atom
nonmetal ion (-)
-
Unit 4: Chemical Bonding
1. Chemical Bond: attraction between the nucleus of one atom and the electrons of another atom.
BARF-Break (bond) Absorb (energy), Release (energy) Form (bond)
Energy Endothermic Exothermic
Definition Bonds are BROKEN & ENERGY
is ABSORBED (reactant)
Bonds are FORMED & ENERGY IS
RELEASED (product)
Is it spontaneous No Yes
General reaction A + energy -->B + C A + B -->C + energy