CHEM 177 : EXAM 1
89 Cards in this Set
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Chemistry
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the study of matter and its transformations
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Matter
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physical material
has mass and volume (elements--> made up of atoms)
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Atoms
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basic building block of an element
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Two types of changes
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physical and chemical
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Physical changes
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changes of state:
melting
mixing
boiling
crushing
flattening
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Chemical changes
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-change in
-composition
chemical reaction
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How do you classify matter
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-by state/phase (solid, liquid, gas)
-by composition
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Solid
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definite shape and volume
can be condensed
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Liquid
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definite volume, indefinite shape
can be condensed
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Gas
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neither definite shape nor volume
compressible
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Heterogenous Mixture
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not uniform
eg. rock/stew
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Homogenous
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uniform matter
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Pure substance
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single substance with distinct properties and compositions
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Homogeneous mixture
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multiple components
eg. sugar, or salt water, jello, alloys, and air
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Elemental substance
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1 type of element
-O2
-gold (pure)
-carbon
---graphite, diamond, nanotubes, buckyballs (all allotropes)
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Compound
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2 or more elements bonded together
-pure water (H2O)
-CO2
-C6H12O6 (glucose)
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Scale in science
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macroscopic (visual-- 1 meter)
Microscopic (10^-6m micrometer)
Submicroscopic/ atomic (10^-9m nano- to 10^-10 m angstrom)
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Atomic Diameter
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.1nm or 1 angstrom
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Pure substance
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matter that has distinct characteristics and a composition that does not vary from sample to sample (water and aluminum)
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3 elements that account for over 90% of the mass of the human body
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carbon, oxygen, hydrogen
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Two kinds of numbers in scientific work
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exact numbers and inexact numbers
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Exact numbers
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values are known exactly
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inexact numbers
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values with uncertainty
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precision
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how closely individual measurements relate to each other
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Accuracy
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how close the measurement is to the true value
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significant figures
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all digits of a measured quantity
the greater the # of sig figs, the greater the precision implied for the measurement
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when are zeros significant
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-intermediate zeros (10.10= 4 sig figs)
-trailing zeros after the decimal (7.3000 =5 sig figs)
-trailing zeros before the decimal point are ambiguous
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When adding or subtracting the answer will have the same number of what
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decimal points as the measurement with the fewest decimal places
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when multiplying or dividing, the answer will have what
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the same number of sig figs as the measurement with the fewest sig figs
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dimensional analysis
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units are multiplied together or divided into each other along with the numerical numbers
-equivalent values cancel each other out
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Conversion factor
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a fraction whose numerator and denominator are the same quantity expressed in different units
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Uncertainty
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expressed in the last digit (uncertain digit)
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Artistotle
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400 B.C.
-matter is continuous (no atoms)
-dominated our thinking for 2000 years
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Democritas
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-400 B.C.
-atoms (indivisible particles
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John Dalton
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-Early 1800s
-atomic theory
-elements are made of characteristic atoms that combine in whole # ratios to form compounds
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1984
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-we first "saw" atoms
-scanning tunneling microscope
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3 important experiments
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1. Cathode Ray Tube
2. oil Drop Experiment
3. Gold foil experiment
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J.J. Thompson
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-1897
-cathode Ray Tube (CRT)
-mass. charge ratio of electron
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Robert Millikan
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-1909
-oil drop experiment
-droplets charged in integrals of 1.6x10^-19 (Fundamental electronic charge)
-also mass of e- --> 9.10 x 10^28g (1/1000 lighter than atoms)
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Ernst Rutherford
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-1910
-Gold Foil Experiment
-discovery of positive, massive, but tiny nucleus
-disproved "plum pudding model"
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Law of conservation of mass
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the total mass of materials present after a chemical reaction is the same as the total mass present before the reaction
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Law of Multiple Proportions
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if two elements A+B combine to form more than one compound, the masses of B that can combine with a given mass of A are in the ratio of small whole numbers
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Atoms are composed of
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subatomic particles
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particles with the same charge
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repel each other
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particles with unlike charges
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attract each other
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J.J. Thompson discovered
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the electron
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atoms are composed of
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protons, neutrons, and electrons
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charge of electron
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-1.602x10^-19 C
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Charge of proton
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+1.602 x 10^-19
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every atom has
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an equal # of electrons and protons (atoms have no net electrical charge)
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atomic number
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# of protons in an atom of any element
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isotopes
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Atoms with identical atomic #s but different mass # (same # of protons but different # of neutrons)
-isotopes of any element are all alike chemically
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periodic table
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arrangement of elements in order of increasing atomic number, with elements having similar properties placed in vertical columns
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Periods
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horizontal rows
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Groups
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verticle columns containing elements with similar properties
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metals
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all elements on the left and in the middle of the periodic table (shiny (luster) malleable/ductility, conductive, lose e- in chem rxns)
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stepped line on periodic table
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separates the metals and nonmetals (From Boron (B) to Astatine (At)
hydrogen is also a nonmetal
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metalloids
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lie along the stair step line and have properties that fall between those of metals and nonmetals
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chemical formula
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how we represent molecules
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diatomic molecule
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a molecule that is made up of 2 atoms (7 @ 7 +H)
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molecular compounds
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compounds composed of molecules contain more than one type of atom
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most molecular substances we encounter contain
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only nonmetals
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molecular formulas
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chemical formulas that indicate the actual #s of atoms in a molecule
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empirical formulas
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chemical formulas that give only the relative # of each type in a molecule (baby #s, smallest possible whole # ratios)
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nonmetals
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dull, brittle, non-conductive (insulating), gain/share e- in chem rxns
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compounds
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2 or more elements bonded together
-two types
1. molecular
2. ionic
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Molecular compound
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nonmetal+nonmetal or acids
two types:
1. organic (Containing C, H)
2. Inorganic (everything else)
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Inorganic molecular compound
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two types
1. binary (2 nonmetals)
2. Acids (release H+ in aqueous solution)
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Ionic compounds
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metal+ nonmetal or polyatomic ion
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Naming of organic molecules
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prefix: meth-, eth-, prop-, but-, pent-, hex
+suffix: (functional group) one C-C bond only= "ane", C=C bond= "ene" C=-C triple bond = "-yne)
OH= "ol" ex. alcohols
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Naming binary inorganic compounds (2 nonmetals)
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prefixes for # of each element
mono
di
tri
tet
*If there is only one of the 1st element, no prefix mono
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Acids
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create H+ in aqueous solution
-usually hydrogen _halogen or polyatomic ion
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Naming acids
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hydro-______ic acid
_____ic acid
depends on polyatomic ions
"ates"=common ions
ClO3--Chlorate SO4 -2-- sulfate PO4 -3-- phosphate CO3-2 carbonate NO3-- nitrate
OH- hydroxide CH3COO- acetate
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Naming ionnic substances (metal + metal)
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metals w/ 1 oxidation= MgO= magnesium oxide
metals w/ multiple oxidation=Fe)= Iron (II) Oxide
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Types of reactions
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1. Synthesis/ combination reaction
2. Decomposition
3. Combustion
4. Single replacement reactions
5. Double replacement reactions
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Synthesis/ Combination reactions
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A+B--> C
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Decomposition
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C--> A+B
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Combustion
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A+O2--> CO2 + H2O
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Single replacement reactions
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A+BC--> AC +B
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Double replacement reactions
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AB+ CD--> AD+BC
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Formula Weights
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sum of atomic weights
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% composition
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mass of individual element/ total mass x100%
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Atomic/ formula weights have two meanings
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1. mass in amu
2. mass in grams of 1 mole of that substance (molar mass)
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Avagado's Number
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1 mole= 6.022x10^23
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Theoretical yield
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maximum product we can make (if things go perfectly, we will get this number)
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Actual yield
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what we actually get from doing the experiment
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% yield
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actual yield/ theoretical yield x100%
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% yield is <_ 100% because
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we could have an incomplete reaction or side reactions or failure to recover or separate the product
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empirical formula
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simplest whole number ratio
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CHEM 177: CHAPTER 1