Chapter 1 and 2 Flashcards
Definition of Chemistry
the science that deals with the materials of the universe and the changes these materials undergo
- seeks to understand what matter does by studying what atoms and molecules do
The world is made up of________ and _________.
matter and energy
Matter
anything that occupies space and has mass
Mass
the number of atoms in an object
Matter is composed of a lot of tiny little pieces we call _________ and _________.
atoms
molecules
Atoms
the tiny particles that make up all matter
In most substances, the atoms are ________ together in units called_________.
bonded
molecules
Molecules
2 or more atoms that are chemically joined
_______ is used to understand mass
weight
Compound
a molecule that is made up of 2 or more different types of elements chemically joined.
Element
matter composed of only one type of atom.
States of matter differ by how much ______ they carry.
energy
Why do the properties of liquids, gases, and solids differ?
because the atoms or molecules have different structures in each state.
All chemicals have some form of _______.
motion
State changes are called ___________.
physical changes; chemical formula stays the same
Chemical change
aka. chemical rxn, physical appearance may change but most importantly chemical formula changes.
The particles of a solid are _________ and are in a ______ position.
packed close together
fixed
-although they may vibrate
The close packing of the particles results in solids being _________.
incompressible
the inability of the particles to move around results in solids retaining their _______ and ________ when placed in a new container; prevents the particles from _________.
shape
volume
flowing
Au is an ___________
atomic element because it is made up of one type of atom
O2 is a___________.
molecular element because it is often found in O2 form
and is made up of 2 atoms (same) in one molecule
H2O is a ___________
molecular compound because water molecules are made up of 2 different types of atoms
The particles in a liquid are closely _______ but they have some ability to move around.
packed
Why are liquids incompressible?
because molecules in a liquid are closely packed
Why are liquids able to take the shape of a container?
the ability of particles to move in a liquid allows liquids to take the shape of the container in which they are placed and to flow. However, they don’t have enough freedom to escape and expand to fill the container.
In which state do particles have complete freedom from each other?
the gas state; the particles are constantly flying around, bumping into each other and the container.
In the gas state, there is a lot of ________ between particles.
empty space
are gases compressible?
yes; because there is a lot of empty space, the particles can be squeezed closer together.
Why do gases flow and expand to take the shape of their container?
because the particles are not held in close contact and are moving freely.
Volume
the amount of space something occupies
Solid
Shape: fixed
Volume: fixed
Compress: no
Flow: no
Liquid
Shape: Indefinite
Volume: fixed
Compress: no
Flow: yes
Gas
Shape: Indefinite
Volume: Indefinite
Compress: yes
Flow: yes
fixed
keeps shape when placed in a container
indefinite
takes shape of the container
How are pure substances classified
Element
Compound; 2 or more chemical elements joined
How are mixtures classified?
Homogenous
Heterogeneous
Matter can be divided into ______ and _______.
Pure substances
Mixtures
Pure substance
composed of only one type of atom or molecule
Mixture
composed of 2 or more different pure substances that are not chemically united, but simply mixed together.
The smallest piece of an element is called a(n) _______.
atom
The smallest piece of a compound is called a _________.
molecule
all molecules of a compound are __________.
identical
each molecule has the same ______ and _______ of atoms.
number
type
Homogeneous
matter that is uniform throughout
- appears to be one thing
- solutions (homogeneous mixtures)
- i.e. salt water
Heterogeneous
matter that is non-uniform throughout
-i.e. oil and water
Physical properties
the characteristics of matter that can be changed without changing its composition
- characteristics that are directly observable.
- i.e. characteristic odor of gasoline
Name the 17 physical properties.
- mass
- solid
- melting point
- taste
- texture
- malleability
- volume
- liquid
- boiling point
- odor
- shape
- ductility
- density
- gas
- volatility
- color
- solubility
Ductility
can be drawn into a wire
Volatility
tendency to convert from liquid to gas readily compared to water
Name the 6 chemical properties
- acidity
- flammability
- oxidizing ability
- basicity (aka alkalinity)
- corrosiveness
- Reducing ability
How do you perform a calculation involving both multiplication/division and addition/subtraction with sig figs?
- follow order of operations
- keep track of sig figs through each step and only round at the end
6.78 x 5.903 x (5.489 -5.01)
6.78 x 5.903 x 0.4790 (only 2 sig figs)
19.1707
~19
G
giga
Basex10^9
M
mega
Basex10^6
k
kilo
Basex10^3
d
deci
Basex10^-1
c
centi
Basex10^-2
m
milli
Basex10^-3
u
micro
Basex10^-6
n
nano
Basex10^-9
p
pico
Basex10^-12
1 inch = _______cm
2.54 cm exactly
1 liter = ______mL
1000mL
1 liter = _________cc
1000 cc
Formula for the volume of a rectangular block
V = l x w x h
Formula for Density
D = m/v
Formula to convert Celsius to Kelvins
K = C +273
Formula to convert Fahrenheit to Celsius
C = (F-32)/1.8
1 calorie (cal) = _________joules (J)
4.184 J
1 Calorie (Cal) = _________calories (cal)
1000 cal
What is the heat capacity of liquid water?
4.184 J/g degrees celsius
Formula for heat capacity
Q = m x Cs x Change in T in Celsius
Q = energy required m = mass in grams of sample Cs = specific heat capacity
What is the formula for change in temperature?
Change in temp =Tf - Ti
Chemical Properties
the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy.
- characteristics that describe the behavior of the matter
- i.e. the susceptibility of iron to rust
When any Hydrocarbon is burned it produces what 2 things?
CO2 (carbon dioxide) and H2O (water)
Physical changes
changes in the properties of matter that do not affect its composition.
- the kinds of molecules don’t change
- i.e. heating water (raises temp but it is still water)
- evaporating butane from a lighter
- dissolving sugar in water (sugar can still be separated from water.
Chemical changes
involve a change in the properties of matter that change its composition
- a chem rxn
- the new substances have different molecules than the original substances
- rusting is iron combining with oxygen to make iron (III) oxide
- burning butane from a lighter changes it into carbon dioxide and water.
Phase changes are ___________.
physical changes
Boiling
liquid to gas
Melting
solid to liquid
Subliming
solid to gas (dry ice CO2(s))
Condensing
gas to liquid
Freezing
liquid to solid
Deposition
gas to solid
State changes require _________ or _________ the substance.
heating
cooling
(occurs by changing the temp)
Separation of mixtures by different physical properties- Distillation
taking advantage of different boiling points of chemicals involved.
Separation of mixtures by different physical properties-Filtration
taking advantage of the different states of matter
Gravity filtration allows for the separation of heterogeneous mixtures
Scientific method
a way that scientists learn about the natural world
Observation
to measure or describe something about the physical world
Qualitative observation
A qualitative observation would be one describing the quality of a thing (e.g. round, blue, hot) without expressing numerical values
Quantitative observation
a quantitative observation, such as the weight or length of an object. Quantitative observations have numbers, such as 3 pounds or 5 meters.
Scientific law
a statement that summarizes past observations and predicts future ones
- usually formulated from a series of related observations
- just states things does not give why.
Hypothesis
a tentative explanation for an observation or scientific problem that can be tested by further investigation.
Experiment
procedures designed to test scientific laws, hypotheses, or theories
Theory
a proposed explanation for observations and laws
-based on one or more well established hypotheses
Precision
the reproducibility of multiple measurements, it is how close the experimental values for different trials are to each other
Accuracy
has to do with how close the experimental results are to the true value.
The last digit of a number is always a _________ the first place of ____________.
guess
uncertainty
Energy
anything that has the capacity to do work
Even though chemistry is the study of matter, matter is affected ____________.
energy
-it can cause physical and/or chemical changes in matter
What are the kinds of Energy?
Kinetic
Potential
Kinetic energy
energy of motion, or energy that is being transferred from one object to another.
Potential energy
energy that is stored; aka energy of postion- can be transformed into kinetic energy
What are the forms of energy?
- Electrical
- Heat/thermal
- Light/radiant
- Chemical
Electrical energy
kinetic energy associated with the flow of electrical charge
Heat/Thermal energy
kinetic energy associated with molecular motion
Light/Radiant energy
kinetic energy associated with energy transitions in an atom.
Chemical energy
potential energy in the attachment of atoms or because of their position.
Heat
(verb) is the exchange of thermal energy between samples of matter
Heat flows from matter that has _____ thermal energy to matter that has ____ thermal energy.
high
low
-until they reach the same temperature
How is heat exchanged?
heat is exchanged through molecular collisions between two samples.
When a process results in the evolution of heat, it is said to be what?
exothermic
-i.e. the burning of a match releases heat (energy)
A process that absorbs energy is said to be what?
endothermic
-i.e. melting ice to form liquid water (requires energy source)
Scientific notation
a system used to write very big or very small numbers in a more compact and precise way.
A number written in scientific notaion consists of a _____ part and an __________ part.
decimal (a # usually between 1 and 10) exponential part (10 raised to some exponent)
Write the following number in scientific notation; 3,456,700
3.4567x10^6
Write the following number in scientific notation; 0.00000012
1.2x10^-7
10^0
1
10^1
10
10^2
100
10^-1
0.1
10^-2
0.01
sig fig rule A
All non-zero digits are significant; 3.14
sig fig rule B
Interior zeros are significant; 3.004
sig fig rule C
trailing zeros are significant when a decimal is present; 300.00
sig fig rule D
leading zeros are NOT significant; 0.0000012
sig fig rule E
exact numbers have infinite sig figs; this includes accurate counting of discrete numbers, defined quantities, and integral numbers
how many sig figs? 8 atoms
according to sig fig rule E1 discrete numbers that are counted accurately have an infinite amount of sig figs
8.00000000…..
how many sig figs? 100cm = 1 m
according to sig fig rule E2 defined quantities have an infinite number of sig figs
look for equal sign
100.00000….cm = 1.0000….m
how many sig figs? D = r/2
according to sig fig rule E3 integral numbers (formulas) have an infinite number of sig figs
the 2 is exact, otherwise formula is false
How do you round using sig figs when multiplying or dividing?
the product or quotient has the same number of sig figs as the number with the lowest number of sig figs
How do you round using sig figs when adding or subtracting?
the sum or the difference has the same number of decimal places as the quantity carrying the fewest decimal places.
How do you round using sig figs when you encounter calculations involving multiplication/division and addition/subtraction?
- follow order of operations
2. keep track of significant figures through each step and only round at the end
Units
previously agreed on quantities used to report experimental measurements
What are the two common unit systems?
English system and Metric system (SI/ International system of units)
What is the SI unit for length?
meter; m
What is the SI unit for mass?
kilograms; kg
What is the SI unit for Time?
seconds; s
What is the SI unit for temperature?
Kelvins; K
Conversion factors
relationships between 2 units; conversion factors are generated from equivalence statements 1 in = 2.54 cm
dimensional analysis
using units as a guide to problem-solving
Derived units
a unit formed from the combination of other units
ex. volume is the measure of 3D space occupied; V is derived from length
ex. Density is mass divided by volume
meniscus
lowest point of concave or highest point of convex
Density
units of mass divided by volume (most commonly expressed as g/cm^3, g/mL, or g/L
Temperature
the measure of the average kinetic energy of the molecules in a sample
Do all molecules in a sample have the same amount of kinetic energy?
No, that is why temperature gives us an average of the kinetic energy of molecules in a sample
a higher temperature means a ______________
larger average kinetic energy
The Kelvin scale has no _________
negative values; real things are always in positive amounts.
What two reference points does the Fahrenheit scale use?
the freezing point of concentrated salt water (0 degrees F) and the supposed average body temp (100 degrees F)
What is room temp in Fahrenheit?
75 degrees F
What are the two reference points for Celsius scale?
the freezing point of DI water (0 degrees C) and the boiling point of DI water (100 degrees C)
What temperature scale is commonly used in science?
Celsius; because they have more reproducible standards
What is room temperature in Celsius?
25 degrees C
Specific heat capacity
(specific heat) the amount of energy needed to change one gram of a substance by 1 degree Celsius.
What is the specific heat capacity of liquid water?
4.184 J/g degrees C
