Exam 1: Chapters 1, 2 and 3 Lecture Notes Flashcards
What is chemistry
The study of the composition and structure of materials and of the changes that matter undergoes
What is matter
Anything that occupies space and has mass
What characteristics of matter change during a reaction
Composition, structure, properties
What is green chemistry
Utilizing a set of principles that encourages alternative ways of generating new and existing chemical products without unnecessary risk to human health and population
What is the purpose of the scientific method
Experiments must be done in a controlled way so that results can be reproduced
What is a hypothesis
a statement that tries to explain something in a common way
What saying was Louis Pasteur known for
“chance favors the prepared mind”
What is the purpose of an experiment
an observation of a natural phenomena carried out in a controlled manor so that results can be duplicated and rational conclusions can be made
What is a theory
A tested explanation of a basic natural phenomenon, we cannot prove a theory to be true
What is a law
A concise statement or mathmatical equation about a fundamental relationship or occurrence in nature
What is the Phlogiston Theory, and an example of it
A theory in the 18th century that said when combustible bodies burn they release “phlogiston”
ex) wood=>burn it=>ash+phlogiston
(thought this because ash weighs less then the wood)
Law of Conservation of Mass
The total mass remains constant during a chemical reaction, and mass is neither created nor destroyed
Characteristics of solid matter
- incompressible
- fixed shape
- fixed volume
Characteristics of liquid matter
- incompressible fluid
- no fixed shape
- fixed volume
Characteristics of gas matter
- compressible
- no fixed shape
- no fixed volume
What is a physical change
- A change in the form of matter (not chemical identity)
- reversible
- no new compounds
What is a chemical change
- transformation of one (or more kinds) of matter into a new kind of matter (or several new kinds of matter)
- new compounds are formed
What is a physical property and an example of it
a characteristic that can be observed for a material without changing its chemical identity
ex) state of matter or color
What is a chemical property and an example of it
a characteristic of matter involving chemical change
ex) acidity or reactivity
Can mixtures be seperated
mixtures can be seperated by physical methods into 2 or more substances
elements
A type of matter that is composed of atoms with the same atomic number (# of protons in the nuclei)
compounds
a substance that contains 2 or more elements
What is the Law of Definite Proportions and who is responsible for it
In a pure compound, the elements are always present in a definite proportion or % by mass (no matter what method of preparation) (Proust)
Law of Constant Composition
a given chemical compound alwas contains its component elements in a fixed ratio
heterogenous mixtures and examples
Components vary and can seperate from eachother
ex) milk, ketchup
homogenous mixtures and examples
uniform composition and properties
ex) vodka
Measurment and their requirements
the comparison of a physical quantity, by measuring with a unit of measurement (fixed standard of measurement)
requires a measured number and the unit
accuracy
how close a measurment is to the true value
precision
how close a set of measurments are to each other
What digits are significant
all non-zero digits are significant
When are zeros significant
- zeros betweem sig figs ex) 606
- zeros to the right of the decimal ex) 2.0
- 9.00 (3 sig figs)
When are zeros insignificant
- zeros to the left of the first nonzero digit ex) .08
- zeros at the end of a nondecimal number ex)900 or 9x10^2
multiplication and division sig fig rule
smallest amount of sig figs
error
difference between the true value and what you estimated or measured
random error
scattered around average value
systemstic error
error due to equitment
temperature and how it flows
measure of “hotness”. heat flows (energy) from an area of higher temp to lower temp
temperature units
- celsius, *C
- fahrenheit, *F
- kelvin, K
Fahrenheit to celsius conversion
C= 5/9 (F-32)
Celsius to fahrenheit
F=(C x 9/5) + 32
Celsius to kelvin
K=C+273.15
equation for force
massxacceleration
pressure
force per unit area
equation for energy
forcexdistance
equation for density
d=m/v
what is the density (and necessary temperature) of water
1 g/mL @ *4 C
What were the 4 postulates of Dalton’s Atomic Theory of Matter
- Elements consist of tiny indivisible particles called atoms
- An element is a type of matter of only one kind of atom, and each atom has the same properties and mass
- Compounds are formed when atoms of different elements combine in small whole-number rations (almost like the law of definite proportions)
- Chemical reactions only involve the rearrangement of atoms present in the reacting substance to give new chemical combinations (almost like the law of conservation of mass)
Dalton’s Law of multiple proportions
If 2 elements form more than one compound the ratios of the masses of the second element to a fixed mass of the first element will also be in small whole numbers
Discovery of the electron (3 people who proved it)
J.J Thompson determined the ratio of the charge to mass by generating a beam of charged particles
Robert Milikan determined the charge and mass of an electron from an oil drop experiment
Marie Curie
Marie Curie coined the term “radioactivity” and discovered polonium and radium
Plum pudding model
- JJ Thompson
- said each atom consists of electrons embedded in a body of positive charge
Ernest Rutherford’s experiment
used positively charged particles to bombard atoms, expecting them to pass straight through. Instead they bounced back
what did ernest rutherford’s experiment prove
- most of the mass in the gold foil was concentrated in dense areas of positively charged particles (nuclei)
- most of an atom’s mass is the positively charged nucleus
Physical structure of an atom
composed of positively charged nucleus surrounded by negatively charged electrons
Atomic symbols
a 1 or 2 letter notation used to represent an element
Isotopes
atoms whose nuclei have the same atomic number (protons) but a different number of neutrons (mass number)
material
each of the particular kinds of matter
ex)the kind of paper or plastic
Brief history of chemistry
- making observations
- developing materials into useful products based on observations
ex) fire=>ceramics
-began to look at precise quantities and substances => central principle of chemistry
atoms
small particles that all material is made up of
molecules
precise arrangements of atoms, can build large molecules from small ones
mass
quantity of matter in a material
matter
whatever occupies space and can be perceived by our senses
Antoine Lavoisier
the first to insist that a balance should be used in chemical research
weight
the force of gravity exerted on an object. it is proportional to the mass/square of the distance between the centerof the mass of the object and the earth
what are the 2 principle ways to classify matter
- physical state (solid, liquid, gas)
- chemical composition (element, compound, mixture)
phase
one of several different homogenous materials present in the portion of matter under study
significant figures
the digits that include all certain digits plus a final digit having some uncertainty
exact numbers
arise when you count items or when you define a unit (9 coins, not 8.5).
atomic mass equation
fractional abundance x percent abundance
mass spectrum
shows relative number of atoms for various masses
percent abundance equation
amu= (% abundance x amu)/100
groups (periodic table)
have related chemical and physical properties (columns)
periods (periodic table)
possess different physical and chemical properties based on how elements react to oxygen (rows)
endangered elements
other than helium, quantities of elements on earth remain constant
what are the 8 groups of main group A elements
- Alkali Metals
- alkaline earth metals
- boron family (triels)
- carbon family (tetrels)
- nitrogen group (pnictogens)
- chalcogens
- halogens
- noble gasses
what is in group b
transition metals
what does the group number tell you?
how many electrons are in the outer shell of the element
what are lanthanides and actinides
14 groups of elements that do not belong to the other 18 groups and are placed at the bottom to conserve space
covalent bonding
sharing of electrons, each atom is attracted to its own nucleus and the nucleus of the 2nd atom so they share
ionic bonding
result of the attraction between cations and anions
Daltons Relative Atomic Masses, and why hydrogen
Dalton devised an experiment to measure an element’s mass relative to the hydrogen atom, because it was believed to be the lightest element
Definition of AMU
The mass of an Atom
Molecular formula
Gives the exact number of different atoms of an element in a molecule
Structural formulas
show how the atoms are bonded to one another in a molecule
Organic compound
Molecular substances that contain carbon combined with other elements for example hydrogen oxygen and nitrogen
Inorganic compounds
compounds composed of elements other than carbon however certain carbon containing compounds are considered inorganic WTF
how are ionic inorganic compounds named
The cation is always named first followed by the name of the anti on most ionic compounds contain both a metal and a nonmetal
how are organic compounds usually named
according to their functional groups
cation
the charge is equal to the group number
anion
charge is equal to the group number -8
do some main group metals with high atomic numbers have more than one cation?
yes
do most transition metals form a cation
yes, more than one, one of which has a +2 charge
when are monotomic cations given the name of the element
if the element forms only one cation (if more than 1 exists it can be written as a roman numeral)
what is the stem of monotomic anions
-ide
polyatomic ions
an ion consisting of two or more atoms chemically bonded together and carrying a net electrical charge
formula units
the group of atoms or ions explicitly symbolized by its formula
how is the formula of an ionic compound written
by giving the smallest possible whole-number ratio of different ions so that the combination is electrically neutral
binary compounds
composed of only 2 elements
how to write binary compounds
name the 1st element using the exact element name
name the 2nd element by writing the stem, with the suffix -ide
binary acids
consist of a hydrogen ion and any anion
oxide
an acid containing hydrogen, oxygen and another element
hydrates
a compund that contains water molecules that are weakly bound in its crystals
how are hydrates named
- first named from the dry compound
- followed by the word “hydrate”
- followed by the prefix indicating the number of water molecules per formula unit
chemical reactions and equations
a chemical equation is the symbolic representation of a chemical reaction, the number of each type of atom on the left must equal that of the right
how to balance an equation
- write the correct formula for the reactants and the products
- balance the elements that appear once in the product
- balance the elements that appear more than once in the product
- check!
molecular mass (and what kind(s) of bonds)
the sum of the atomic masses of all the atoms in a molecule (covalent molecules)
formula mass (and what kind(s) of bonds)
the sum of the atomic masses of all atoms in a formula unit of the compound (covalent and ionic molecular compounds)
what is the AMU of 1 carbon 12 atom
1 amu
why was carbon 12 picked to be the basis of AMU
because it is stable, solid and nontoxic
how to convert amu to s
use avogadro’s number!
6.022 x 10^23
how much is 1 mole
6.022 x 10^23 things
how many grams is 6.022 x 10^23
12 g
relationship between the mass (g) to amu
the mass (g) of 1 mole is equal to the relative atomic mass of the element
equation for amu and g
moles=mass of compound/molar mass of compound
or
moles=100g x 1 mol/x grams
how to find the percent composition
- find the milar mass
- divide mass (amu) by total mass of compound, multiply by 100
empirical formula
the simplest formula for a compound. its the formula of the substances written with the smallest integer (whole number) subscripts
the percent composition of a compound leads directly to this
limiting reagants
when reactants are not added according to precise stoiciometry
ultimately determines how
much product can be obtained.
Stoichiometry
the calculation of the quantities of reactants and
products involved in a chemical reaction.
Theoretical Yield
is the amount of product that would result if all
the limiting reagent reacted.
Actual Yield
is the amount of product actually obtained from a
reaction.
percentage yield
the actual yield (experimentally
determined) expressed as a percentage of the theoretical yield
(calculated).
(Actual Yield/Theoretical Yield) x 100
