Exam #1

Temperature
In Kelvin
volume
Derived unit:
lxwxh
Density
mass/volume
accuracy
the closer you are to the “true” value the more accurate is your result.
Precision
the smaller spread of values the more precise your results are.
Mean
summation of all numbers divided by the total amount of numbers.
systematic errors
flaw in tools or instruments
random errors
occure equally in each direction
Personal Error
didn’t read the out come correctly, lost stuff, sloppy.
atoms
smallest particle of an element
metalloids
have a similar properties of metals and nonmetals, metal want to react with non metals
Intensive properties
Do not depend on quantity or amount.
EX. Density
Extesisve properties
depends on amount
Mass number
is the number of protons and neutrons.
Isotopes
atoms of the same element but different mass numbers. Electrons and protons are the same but different number of neutrons.
Atomic Mass Unit (AMU)
a convenient unit of mass; 1/12th the mass of a 12/6C atom
Mole
one mole is the number of atoms in 12g of 12/6C
molar mass
the mass of 1 mole of substance; equal to the molecular or formula mass of the substance in grams.
atomic mass
the weighted average mass of an element’s atoms
Ionic Compounds
metal with non metal
molecular compounds
nonmetals reacting
covalent compound
two nonmetals reacting
% composition
(weight of an atom in 1 mol of compound)
______________________________________
(total weight of 1 mol of compound)
% composition
(weight of an atom in 1 mol of compound)
______________________________________
(total weight of 1 mol of compound)
% composition
(weight of an atom in 1 mol of compound)
______________________________________
(total weight of 1 mol of compound)
empirical formula
a formula that gives the rations of atoms in a compound
molecular formula
a formula that tells the identity and numbers of atoms in amolecule
molarity
a common unit of concentration; the number of moles of solute per liter of solution. Mols/L
Phsyical properties
characteristics that do not involve a change in chemical makeup.
chemical properties
characteristics that do involve a change in chemical makeup
metals
shiny most solid at room temp. conduct head and electricity. malleable
nonmetals
not shiny, brittle, brightly colored, poor conductors of heat and electricity
metalloids
properties are between metal and non metal. MOst are silvery, solid at room temp burttle TEND to be poor conductors of heat and electricity.
mass
amount of matter
matter
describe antyhing with physical presence, anything with mass
celsius to fahrenheit
‘F= (9’F/5’C x ‘C) +32’F
Law of mass conservation
mass is neither created nor destryoed in chemical reactions
Law of definite porportions
different samples of pure chemicalsubstace always constains the same proportion of elements by mass
Law of Multiple Proportions
Elements can combine in different ways to form different substances whose mass rations are small whole-number multiples of eachother
Electrons
negatively charged particles in all substances
cathode ray
the visible glow emitted when an electric potential is applied between two electrodes in an evacuated chamber.
nucleus
concentrated mass in a tiny central core
protons
positively charged particle in nucleus with a mass of 1.672622 x 10 -24 g
Neutrons
almost identical mass to protons but with not charge
alpha particles
a type of emission previously observed to be given off by a number of naturally occurring radioactive elements.
chemical compounds
is a pure substance that is formed when atoms of two or more elements comvine and create a new material with properties completely unlike those of its constituent elements.
chemical reactions
transformation of one substance to another
chemical equation
lists the symbols of the individual constituent elements and indicates the number of atoms of each element with a subscript
mixtures
a blend of two or more subsances added together in some random proportion without chemically changing the individual substances themselves.
heterogenius mixture
are those in which mixing is not uniform and which therefore have regions of different composition
homogeneous mixtures
are thos in which the mixing is uniform and has a constant composition
chemical bonds
electrons forming connections between atoms together in compounds
covalent bonds
most common: result when 2 atoms share electrons
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