Notes

CH 1 ATOMS

chemistry - the science that seeks to understand the properties of matter by studying the structure of the particles that compose it

matter - anything that occupies space & has mass (quantity of matter in a material)
1. matter is particulate - it is composed of particles
2. the structures of those particles determines the properties of matter

atoms - basic submicroscopic particles that constitute the fundamental building blocks of ordinary matter; an extremely small particle of matter that retains its identity during chemical reactions
chemical reaction - a process by which atoms are rearranged in reacting substances to produce new chemical combinations in substances formed by the reaction
molecules - substances formed when 2 or more atoms bond (come together) in specific geometric arrangements
substance - a specific instance of matter (ex: air, water, sand)

classification of matter:
1. state - classification of the physical form of matter as a solid, liquid, or gas; changes from solid to liquid to gas /w increasing temperature
2. composition - types of particles that compose matter

states of matter:
solid - particles are tightly packed in a fixed volume & fixed shape
liquid - particles are closely packed but can move; fixed volume but not a fixed shape
gas - particles are widely spaced; lacks a definite volume or shape
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composition:
INSERT MATTER COMPONENTS CHART

pure substance - a substance composed of only 1 type of particle
mixture - a substance composed of 2 or more different types of particles that can be combined in variable proportions

a pure substance can be either:
a) element - a substance composed of only 1 type of atom; cannot be broken down into simpler substances (ex: helium)
b) compound - a substance composed of atoms of 2 or more elements in fixed, definite proportions (ex: water)

a mixture can be either:
a) heterogeneous - a mixture where the composition varies from 1 region to another; different particles do not mix
b) homogeneous - a mixture /w the same composition throughout; different particles mix
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3 laws supporting the atomic theory:

1. law of conservation of mass: in a chemical reaction, matter is neither created nor destroyed
mass of reactants = mass of product

2. law of definite proportions "law of constant composition": all samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements
ex: decomposition of 18 g of water (H2O) = 16 g of oxygen (O) & 2 g of H (hydrogen) or:
mass ratio = 16.0 g O/2.0 g H = 8.0 or 8:1

3. law of multiple proportions: when 2 elements (A & B) form 2 different compounds, the masses of element B that combine /w 1 g of element A can be expressed as a ratio of small whole #s.
Ex: Carbon & oxygen form both carbon monoxide & carbon dioxide. The mass ratio of oxygen to carbon in carbon dioxide is 2.67:1, so 2.67 g of oxygen reacts /w 1 g of carbon. In carbon monoxide, the mass ratio of oxygen to carbon is 1.33:1, or 1.33 g of oxygen to every 1 g of carbon. The mass ratio of the 1 is: mass O to 1 g of C in CO2/mass O to 1 g of C in CO = 2.67/1.33 = 2

john dalton's modern atomic theory:
1. each element is composed of tiny, indestructible particles called atoms
2. all atoms of a given element have the same mass & other properties that distinguish them from atoms of other elements
3. atoms combine in simple, whole-number ratios to form compounds
4. atoms of 1 element cannot change into atoms of another element; in a chemical reaction, atoms only change the way they are bound together /w other atoms

structure of the atom:
INSERT ATOM DIAGRAM

nuclear theory:
1. most of the atom's mass & all of its positively charged protons are contained in a small core called the nucleus
2. most of the volume of the atom is empty space, throughout which tiny, low-mass, negatively charged electrons are dispersed
3. there are as many negatively charged electrons outside the nucleus as there are positively charged protons within the nucleus, so that the atom is electrically neutral

neutron - an electrically neutral subatomic particle found in the nucelus of an atom /w a mass almost equal to that of a proton

atomic mass unit (amu) - a unit used to express the masses of atoms & subatomic particles; defined as 1/12 the mass of a carbon-12 atom contianing 6 protons & 6 neutrons
-the mass of a proton or neutron is approximately 1 amu; electrons have an approximate mass of 0.00055 amu
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atomic number (Z) - the # of protons in an atom; the atomic number defines the element & the charge of the nucleus
ex: carbon has 6 protons so it has a nuclear charge of 6+

chemical symbol (x) - a 1 or 2 letter abbreviation for an element that is listed directly below its atomic number on the periodic table
ex: C is carbon

isotopes - 1 of 2 or more atoms of the same element /w the same # of protons but different #s of neutrons & consequently different masses
natural abundance - the relative % of a particular isotope in a naturally occuring sample /w respect to other isotopes of the same element
ex: neon atoms - 90.48% are the isotope /w 10 neutrons, 0.27% are the isotope /w 11 nutrons, & 9.25% are the isotope /w 12 neutrons

mass number (A) - the sum of the # of protons & neutrons in an atom

INSERT ISOTOPE DIAGRAM
ex: Ne-20 or 20/10 Ne

ions - an atom or molecule /w a net charge caused by the loss or gain of electrons
cation - a positive charged ion that has lost an electron; written X+
anion - a negatively charged ion that has gained an electorn; written X-

atomic mass (atomic weight): the average mass in amu of the atoms of a particular element based on the relative abundance of the various isotopes; numerically equivalent to the mass in grams of one mole of the element
Ex: Chlorine: 75.77% chlorine-35 atoms (mass 34.97 amu) and 24.23% chlorine-37 atoms (mass 36.97 amu)
Atomic mass of chlorine = 0.7577 (34.97 amu) + 0.2423 (37.97 amu) = 35.45 amu

atomic mass equation:
Atomic mass = (fraction of isotope 1) x (mass of isotope) 1 + ...

mass spectrometry: seperates particles according to mass
1. mass of atoms
2. percent abundance of isotopes of element

moles (mol):
Avogadro's Number: 1 mol = 6.02214 x 10^23 particles
-value of 1 mole is = to the # of atoms in 12 g of pure Carbon-12

Converting btwn Moles & Atoms:
1 mol atoms/6.022 x 10^23 atoms or 6.022 x 10^23/1 mol atoms

Insert examples:
a) # of copper atoms in 2.45 mol of copper

molar mass - mass in grams of 1 mole of atoms of an element; numerically equivalent to the atomic mass of the element in amu
Ex: 12.01 g of C or 12.01 g C/mol C or 1 mol C/12.01 g C
Insert example:
a) given 0.0265 g C, find mol C
b) given 3.10 g Cu, find Cu atoms

periodic table - the table that arranges all known elements in order of increasing atomic number; elements with similar properties fall into rows & columns

1. period: elements in 1 horizontal row
2. group: elements in 1 vertical column

metal: substance or mixture that has a characteristic luster or shine & is generally a good conductor of heat & electricity
nonmetal: an element that doesn't exhibit the characteristics of a metal
metalloid: an element having characteristics of both metals & nonmetals; semiconductors