chemistry
average atomic mass formula
(mass)(%)+(mass)(%)/100
Calculating empirical formula
-Pretend that you have a 100g sample. That is, change % to grams. -Convert the grams to moles for each element. -Divide each number by the smallest number. -Multiply the result(if needed) to get rid of any fractions.
Acid Nomenclature
-ides go to hydro__ic acids -ates go to -ic acid -ites go to -ous acid -if hyper/per prefixes = keep same
Atomic Theory of Matter
1. all matter is made of atoms. 2. all atoms of an element are identical. 3. diff elements have diff atoms. 4. atoms keeps properties in chem reaction
1 mole of 12C has a mass of
12.000g
converting moles to a number
2 mol x 6.022 x 10^23 1 mol
PRACTICE: How many protons (p) and electrons (e) are found in a Se²⁻ ion?
34 p, 36 e Se has an atomic number of 34, so it contains 34 protons. The neutral atom would have 34 electrons, but because the ion has a -2 charge, this indicates that there are two additional electrons.
1 mole equals
6.022 x 10^23 of anything
chemical change
A change in matter that produces one or more new substances
polyatomic ion
A charged group of covalently bonded atoms
physical change
A physical change in a substance that does not change its identity
compound
A substance made up of atoms of two or more different elements
Metalloids are located
Along the zig zag line
Parallax
An apparent shift in the position of an object when viewed from different locations
matter
Anything that has mass and takes up space
Isotopes
Atoms of the same element that have different numbers of NEUTRONS (aka diff mass)
atom
Basic unit of matter
PRACTICE: Predict the chemical formula for the ionic compound formed by Ca²⁺ and ClO₃⁻
Ca(ClO₃)₂
Changes in states of matter
Condensation, Evaporation, Sublimation, Melting, Freezing
PRACTICE: Predict the chemical formula for the ionic compound formed by Cu²⁺ and P³⁻
Cu3Pu2
What are the diatomic elements?
H2, N2, F2, O2, I2 Cl2, Br2, Have No Fear Of Ice CoLd BeeR
atomic mass
Number of protons and neutrons
when multiplying/dividing sig figs
The answer must have the same amount of sig figs as the number with the least amount of sig figs in the question. Ex. 76.54x0.0086 = 0.66 <-- because 0.0086 only has 2 sig figs.
Oxyanion Nomenclature
When there are two oxyanions involving the same element: -The Fewest oxygens start with Hypo- and end in -ite -The 2nd fewest oxygens ends in -ite -The 2nd most oxygens ends in -ate. -The Most oxygens start with Per- and end in -ate
This is a:
chemical change
Molecular compounds are usually
composed of two or more nonmetallic elements
PRACTICE: What is the correct IUPAC name for CuNO₃?
copper (I) nitrate
when rounding off calculated answers, if the number is 5, round to the
even number
periodic table columns are
groups
protons and neutrons are the only particles that
have a charge
PRACTICE: What is the correct IUPAC name for HCN(aq)?
hydrocyanic acid
When atoms lose or gain electrons they become
ions
formula weight (FW)
is the sum of the atomic weight (AW) of atoms in the chemical formula of a substance
protons and neutrons have essentially the same
mass
Density is
mass/volume
ionic compounds are formed between
metals and nonmetals
Anions
negatively charged ions (gain electrons) (right side)
PRACTICE: What is the correct IUPAC name for HNO₃(aq)?
nitric acid
periodic table rows are
periods
H20 (l) --> H20 (s) is a
physical change
Cation
positively charged ion (lost electrons) (left side)
Nonmetals are located
right
PRACTICE: What is the correct IUPAC name for Ag₂S?
silver sulfide
elements in the same group have
similar chemical properties
homogeneous mixture is also called a
solution
Density is the physical property of a
substance
PRACTICE: What is the correct IUPAC name for As₄O₃?
tetrarsenic trioxide
molar mass
the mass of one mole of a substance
Atomic number
the number of protons in the nucleus of an atom
percent composition
the percent by mass of each element in a compound
emperical formula
the smallest whole number ratio of the atoms in a compound
molecular weight (MW)
the sum of the atomic weights of its atoms
When adding/subtracting sig figs
use the same number of decimal places as the measurement with the fewest decimal places