Chemistry final Flashcards
(93 cards)
1
Q
Mathematics
A
A study of relationships among numbers
includes measurements and calculations
2
Q
Scientific method
A
A formal method for doing science
3
Q
Technology
A
The application of scientific knowledge
4
Q
Observations
A
Made by observing, describing, and measuring an event in nature
observations can be data
Qualitative and quantitative
5
Q
Qualitative data
A
Descriptive information
6
Q
Quantitative data
A
Numerical information
7
Q
Hypothesis
A
A possible interpretation of observations
If (procedure), then (prediction), because (explanation)
8
Q
Experiments
A
Tests that determine how well a hypothesis explains observations
Results may or may not accept the hypothesis
9
Q
Theory
A
An explanation of facts and well-tested hypotheses
Can evolve over time as new knowledge is gained
10
Q
Independent variable
A
X-axis
The variable that is purposefully changed in an experiment
Manipulated variable
There’s only 1 independent variable in an experiment
11
Q
Dependent variable
A
Y-axis
The variable that is measured in an experiment
Manipulating the independent variable causes changes to the dependent variable
Responding variable
12
Q
Constant variable
A
The variables that remain the same between the experimental and control groups
13
Q
Control group
A
The group to which no changes have been made
Serves as a standard for comparison
14
Q
Measurement
Length
A
Metric unit: Meter (m)
SI unit: Meter (m)
Tool: Metric ruler
15
Q
Measurement
Volume
A
Metric unit: Liter (L)
SI unit: Cubic centimeters (cm^3)
Tool: Graduated cylinder
16
Q
Measurement
Mass
A
Metric unit: gram (g)
SI unit: kilogram (kg)
Tool: Scale
17
Q
Measurement
Temperature
A
Metric unit: Celsius (C)
SI unit: Kelvin (K)
Tool: Thermometer
18
Q
Measurement
Time
A
Metric unit: Seconds (s)
SI unit: seconds (s)
Tool: Stopwatch
19
Q
Exact numbers
A
Obtained by counting items or using a definition that compares two units in the same measuring system
20
Q
Measured numbers
A
The numbers you obtain when you measure a quantity
21
Q
Accuracy
A
How close the measurements are to the true or accepted value
22
Q
Precision
A
How closely grouped a set if data is
23
Q
Percent error
A
|experimental value-accepted value|/accepted value x 100
24
Q
Density
A
A physical property of matter that compares the mass of a substance to the volume
25
Uses of density
1. Identifying a specific substance
2. Determining the purity of a substance
3. Predicting if an object will sink or float in a liquid or air
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Substances with high densities...
Particles that are closely spaced
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Substances with low densities...
Have particles that are farther apart
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Density formula
Density=Mass/volume
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Volume of a rectangle formula
length x width x height
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Displacement method
-A starting volume of water is measured
-The object is submerged into the sample of water
-The final volume of the object and water is measured
-The difference between the starting and final volume of the water, or the amount of displacement water, equals the volume of the irregularly shaped object
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Democritus
All matter, plus space and time, is composed of tiny, indestructible units called atoms. Atoms are...
- Completely solid with no internal structure
-Differ in their sizes, shapes, and weights
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John Dalton
Determined that each chemical element is composed of a unique type of atom
The atoms of an element are identical in their masses
Atoms of different elements have different masses
Atoms only combine in small whole number ratios to form compounds
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J.J. Thompson
Atom composed of positively and negatively charged particles
Plum pudding model
Came up with electrons
34
Ernest Rutherford
Conducted the gold foil experiment from which he deduced the following about an atom:
Small regions in the center of the atom (nucleus) contain positive protons
Negative electrons occupy the region of space around the nucleus
Most of an atom is empty space
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Niels Bohr
Developed a conceptual model of the atom using quantum theory in which electrons orbit the nucleus in fixed paths
36
Quantum mechanical model
Based on the work of several scientists
Electrons show wavelike behavior
It is impossible to know at any given time both the position and energy of an electron
Electrons are found in atomic orbitals or regions within an atom where electrons are likely to be 90% of the time
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The atom
The smartest particle of an element that retains the characteristics of that element
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Brownian motion
random movement displayed by small particles that are suspended in fluids
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Subatomic particle: Proton
Symbol: p or p^+
Relative charge: 1+ (positive)
Location in atom: Nucleus
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Subatomic particle: Neutron
Symbol: n or n^0
Relative charge: 0 (neutral)
Location in atom: Nucleus
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Subatomic particle: Electron
Symbol: e or e^-
Relative charge: 1- (Negative)
Location in atom: Orbits outside the nucleus
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Atomic number
The number of protons contained in each atomic nucleus
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Charge of atoms?
Atoms are electrically neutral meaning the number of protons equals the number of electrons
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Mass number
The sum of the number of protons and the number of neutrons
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APE
Atomic number=number of protons=numbers of electrons
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MAN
Mass number-atomic number=number of neutrons
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Average atomic mass formula
A.A.M=(Mass x % )+(Mass x %)
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Most common isotope
Finding the most common isotope generally can be determined by looking at the average atomic mass and determining which mass number of isotopes its closes to
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Isotopes
An element has a definite number of protons in each of its atoms, but the number of neutrons may vary
They share the same physical properties even if their physical property of mass differs
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Nucleotide notation
Has the mass number in the upper left corner and the atomic number in the lower left corner next to the left of the element symbol
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Hyphen notation
Has the name or symbol of the element followed by a hyphen and the mass number of the isotopes
Ex. Carbon-12 or C-12
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Dmitri Mendeleev
Arranged the 60 known elements of the time into a periodic table
Elements were arranged by increasing atomic mass
Elements were grouped based on similar properties
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Families/groups
Vertical columns
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Periods
Horizontal rows
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representative elements
First two groups and last six groups on the periodic table
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Alkali metals
Group 1A or 1
Soft and shiny
React vigorously with water and form white products when they combine with oxygen
Hydrogen is not an alkali metal
Name derived from arabic word for ashes
one valence electron
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Alkaline earth metals
Group 2A or 2
Soft, shiny metals
Only found in minerals and compounds and not in their elemental form in nature
Named because they form alkaline solutions when mixed with water and because they are found in fire-resistant substances which were referred to as "earth" substance by early alchemists
two valence electrons
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Transition metals
Group 3B-2B or 3-12
Elements that exhibit metallic properties such as ductility, malleability, conduction of heat and electricity, and magnetism
No common pattern of valence electrons
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Halogens
Group 7A or 17
Highly reactive
Form compounds with most of the elements
Named because they tend to form salts
"halogen" means salt-forming in Greek
60
Noble gases
Group 8A or 18
Unreactive elements
Possibly named because they tend to not combine with other elements, similar to how nobility were above interacting with common folk
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Metals
Located to the left if the zigzag line on the periodic table
Shiny, opaque
Most are solid at room temperature
Ductile and malleable
Good conductors of heat and electricity
Hydrogen acquires the properties of a liquid metal only at high pressures and normally behave as a nonmetallic gas
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Nonmetals
Located to the right of the zigzag line on the periodic table
Dull, may be transparent
Can be solid, liquid, or gas at room temperature
brittle and shatter when hammered
Poor conductors of heat and electricity
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Metalloids
Located along the zigzag line on the periodic table except aluminum
Have both metallic and non-metallic properties
Weak conductors of heat electricity which makes them useful as semi-conductors
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Covalent compound
A substance made up of atoms which are held together by covalent bonds
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How are two atoms held together?
Their mutual attraction for valence electrons
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Molecule
Any group of atoms held together by covalent bonds
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Bonding pairs
Electrons found in a single covalent bond
One electron comes from one of the atoms taking part in the covalent bond, the other electron comes from the other atom taking part in the bond
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Non-bonding pairs
Electrons that exist in the valence shell of an atom but are not part of the covalent bond
69
Writing names of molecular compounds
Two non-metals
-The first non-metal in the compound is named by its elemental name
The second nonmetal in the component is named using the first syllable of its elemental name with the ending changed to ide
Uses prefixes
The prefix mono is omitted from the first non-metal
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Double covalent bond
Occurs when 4 electrons are shared between two atoms
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Triple covalent bond
Occurs when 6 electrons are shared between two atoms
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Diatomic molecules
Contain two like atoms
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Valence electrons
The electrons of the outermost energy shells in any atom are directly exposed to the external environment and are the firs to interact with other atoms
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What do valence electrons do?
Are involved in chemical bonding
Related to the group # of an element
Determine the chemical properties of an element
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Octet rule
8 is the magic number
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Ions
When a valence electron is lost or gained, the balance is upset and the atom then has net electric charge
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Cations
Lose there electrons easily
Form metals
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Anions
Non-metals gain electrons easily and form anions
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Electron transfer
When an atom that tends to lose electrons comes in contact with an
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Ionic bond
Electrically neutral
Typically forms working
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Naming ionic compounds
Cation stays in its elemental name and take the first syllable of the anion and add "ide" to the end
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Collision theory
- Collision (the reactants must collide)
- Orientation (The reactants must align properly)
- Energy (Activation energy, enough energy for collision to occur)
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Activation energy
Minimum amount of energy for a reaction to take place
84
Temperature and collisions
At higher temperatures the increase in kinetic energy makes the reacting molecules move faster resulting in more high energy collisions
85
Concentration/reactants
At higher concentrations, more molecules increase the chance of more molecular collisions
86
Catalysts
Speeds up a chemical reaction by providing an alternate pathway for bonds
Catalysts lower activation energy
87
Equilibrium
The "stopping point" of a reversible reaction where the reaction doesn't stop but the amount of reactants and products has leveled out
88
Le chataliers principle
States that change in variable to a reaction at equilibrium will cause the reaction to change to restore equilibrium
If you add more of something to a side shift away from that side and add to the other side
If you take something away from a side the reaction shifts towards that side
89
Heat of reaction
the energy that is released or absorbed when chemicals are transformed in a chemical reaction
90
How were non-renewable resources made?
when prehistoric plants and animals died and were gradually buried by layers of rock
91
Atomic size/atomic radii
Determined by the distance of valence electrons from the nucleus
92
Ionization energy
The energy needed to remove an electron
93
Electronegativity
Ability to attract electrons
