Chemistry is the study of the composition, structure, and properties of matter and of changes (transformations) that occur in matter.

Chemical laws describe the changes that take place in nature, and chemistry is deeply involved in the profound social changes of the past two centuries.

Chemistry is a basic science whose central concerns are:
1.  The structure and behavior of atoms (elements);
2.  The composition and properties of compounds;
3.  The reactions between substances with their accompanying energy exchange; and
4.  The laws that unite these phenomena into a comprehensive system.

What is a chemical?
A substance produced by or used in a chemical process. Webster's II
A substance (such as an acid, alkali, salt, synthetic organic compound) produced by or used in a chemical process or used for producing a chemical effect. May 9, 1994, C&EN, p. 3

Chemicals can be represented (symbolized) by:
Chemical Formula   C₁₂H₂₂O₁₁
Structural Formula

Nomenclature
    a-D-Fructofuranosyl-b-D-glucopyranoside

Common Names
    Saccharose
    Sucrose
    Table sugar

Matter is the building block material of the universe. It is anything that takes up space and has mass.

A substance is a type or form of matter, which has a definite (constant) composition and distinct properties. A substance is a single, pure form of matter, even on the microscopic level.

A physical property is a characteristic of a substance, which can be observed or measured without changing the composition or identity of that substance.  A substance can be identified by its physical properties. Physical properties include: temperature, pressure, mass, volume, state (solid, liquid, gas), melting point, boiling point, density, color, crystal shape, hardness or brittleness, heat capacity, thermal conductivity, electrical conductivity.

A physical change is a process that occurs without a change in chemical composition or identity of a substance. A physical process does not change a substance into another substance.

Melting wax is an example of a physical change.   It can by represented as:  C₅₀H₁₀₂(s) ---> C₅₀H₁₀₂(l)

Temperature is a measure of how hot or cold an object is relative to another object. It is the property of an object that measures the amount of random energy of motion of its molecules and determines the direction of spontaneous heat flow.

Three Scales for Measuring Temperature

Reference	Fahrenheit	Celsius	Kelvin
Water MP	32 oF	0 oC	273.15 K
Water BP	212 oF	100 oC	373.15 K

Interconversions Between Temperature Scales
K = 273.15 + ^oC (The temperature interval of ^oC and K are equal.)
T_F = (1.8 x ^oC) + 32 or [9/5 T_C] + 32
T_C = (F^o - 32)/1.8 or [T_F - 32](5/9)

Example Temperature Conversion
98.6 ^oF = ? K
T_C = [T_F - 32 ^oF](5/9)
T_C = [98.6 ^oF - 32^oF](5/9) = 37.0 ^oC
K = 273.15 + ^oC = 273.15 + 37.0 ^oC = 310.2 K

Density (d) is the ratio of mass to volume. d = mass / volume

Example Density Problems
1.  What is the density of a sample of metal that has a mass of 118.26 g and a volume of 43.8 mL?
    density =       mass     =    118.26 g     = 2.70 g/mL
                         volume             43.8 mL
2.  What is the mass in grams of a 9.00 cm³ piece of lead? The density of lead is 11.3 g/cm³.   [102. g]

3.  What is the volume of a sample of mercury that has a mass of 938.22 g and a density of 13.5 g/mL?
        volume = [938.22 g][1 mL/13.5 g] = 69.498 mL

4.   When a 26.048 g sample of metal was placed in a graduated cylinder containing water, the water
       level rose from 25.0 mL to 28.31 mL.   What is the density of the metal?    [7.9 g/mL]

Dimensional Analysis and Problem Solving
What volume of ethanol will have the same mass as a 50.00 mL volume of mercury?
    (50 mL )(13.5 g /mL) = 675. g
    (675 g)(1 mL/0.798 g) = 845.9 mL

A proportionality factor is a ratio (fraction) derived from an equality statement and whose numerator and denominator have differing units but refer to the same thing. It is also referred to as a conversion factor.

Because 1 in = 2.54 cm, the ratio of 1 in./ 2.54 cm or 2.54 cm / 1 in. could be used as a conversion factor.

A chemical property describes a substance's composition and its reactivity. It describes how the substance reacts, or changes into other substances (e.g., iron rusts and a candle burns).  A substance can be identified by its chemical properties.

Burning a candle is an example of a chemical change and can be represented by:
2 C₅₀H₁₀₂(s) + 151 O₂(g) ---> 100 CO₂(g) + 102 H₂O(g)

Energy
The universe is composed of matter and energy. Matter includes all tangible things, and has mass and volume that can be measured. The concept of energy is more difficult to grasp because energy is intangible. Energy, unlike matter, cannot be held in your hand.

Energy (Greek energhs "work within") can be defined as the capacity to do work (move matter) or produce heat. A wound clock acquires "something" with which it can do work. This "something" that enables the clock to do work is energy.

Energy comes from compression of atoms in a material, separation of attracting bodies, rearrangement of electric charges in the molecules of a substance.

A heterogeneous mixture has physically distinct parts, each with different properties. Often, the nonuniformity of the composition of a heterogeneous mixture can be observed without magnification or a microscope (e.g., oil & water; concrete).  Sometimes magnification is necessary to observe that a mixture is heterogeneous (e.g., blood).  Properties in one region of a heterogeneous mixture will be different from the properties in another region.

A homogeneous mixture (solution) is a mixture uniform in its properties throughout
(e.g., gaseous: air; liquid: Coca Cola; solid: brass).
Only on the atomic level can differences be seen in a homogeneous mixture.

Separation processes could include filtering, magnetic separation, or boiling.

Physical States of Matter

STATE	SHAPE	VOLUME	COMPRESSIBLE
Solid	Fixed	Fixed	NO
Liquid	Fixed	Fixed	Relatively incompressible
Gas	No fixed shape	No fixed volume	YES

Macroworld is a term used to describe natural phenomenon when large objects and large amounts of energy are involved.

Macroscale denotes quantities and characteristics that can be observed with the unaided eye.

Microworld is a term used to describe natural phenomenon when small objects and small amounts of energy are involved, as in the case of atoms and molecules.

Microscale quantities are observed only with the aid of special instruments. The microscopic world is largely hidden from our senses and our common sense.

Nanoscale is on the level of size where matter is in the nanometer range.

An atom is the smallest distinctive unit in a sample of matter that can be chemically altered. Atoms are electrically neutral.

A molecule can be defined as:
- a definite group of atoms that are chemically bonded together--that is, tightly connected by attractive forces. (Ebbing, 5th ed.)
- a neutral particle composed of two or more atoms combined in a definite ratio of whole numbers. Brady & Holum, 2nd ed.
- the smallest particle of an element or compound that has the chemical properties of the element or compound. (p. 15) Umland, 1993

The Kinetic-Molecular Theory states that matter is constantly moving on the molecular level.
The amount of movement is dependent upon state and temperature.

Particles in the solid state are packed closely together and are restricted in movement.
Their movement is restricted to vibrational types of movement.

Particles in the liquid state are relatively close to one another but are not as restricted in space as the particles
in a solid and therefore can move from place to place in the liquid.
This movement is referred to as translational.

Particles in the gaseous stateare the least restricted and move chaotically within the vessel that confines them.
The distance between two gas particles is much, much larger than the actual size of the gas particle itself.
The speed at which the gas particle moves can be well over 1000 mph.

Movement is directly proportional to temperature.  The higher the temperature, the greater and faster the movement.

An element is a substance that cannot be decomposed into a simpler substance by a chemical process.
Atoms that are identical in chemical and physical properties are elements.

The Atomic Theory
1. All matter is composed of indivisible atoms, which are extremely small.
2. An element is a type of matter composed of only one kind of atom, and the chemical properties of each of
the atoms of a given element are identical.
3. A compound is composed of atoms of two or more elements that have been chemically combined.
4. A chemical reaction consists of rearrangement of the atoms present in the reacting substances to give
a new substance. The atoms cannot be destroyed or created in this process.

Antoine Lavoisier (1743-1794) found that the total mass of a chemical reaction remains constant.
He formulated the Law of Conservation of Mass which states that the total mass remains constant
during a chemical reaction.

EXAMPLE:
When 2.53 g of mercury was heated in the presence of oxygen, 2.73 g of a red-orange solid were produced.
What mass of oxygen was reacted?

Mercury + oxygen -----> red-orange solid
2.53 g             ? g                       2.73 g

2.73 - 2.53 = 0.20 g oxygen

In a given chemical compound, the elements are always combined in the same proportions by mass.
1.0000 g of NaCl contains 0.3934 g Na and 0.6066 g of chlorine.  This gives a ratio of 0.3934 g Na/0.6066 g Cl
or  0.6485 g Na/g Cl.

1.0000 g of carbon monoxide (CO) contains 0.4288 g of C and 0.5712 g of O.

That means there is a ratio of 0.7507 g C/ 1 g O  or  1.332 g O/ 1 g C

1.0000 g of sodium sulfate (Na₂SO₄) contains  0.3238 g of Na, 0.4506 g O, and  0.2257 g S

A 1.7757 g sample of Na₂SO₄ would decompose to yield:
    0.5748 g of Na
    0.4009 g of S
    0.8000 g of O

John Dalton formulated the Law of Multiple proportions which states that when two elements form more
than one compound, the masses of one element in these compounds for a fixed mass of the other element
are in ratios of small whole numbers.

In carbon monoxide (CO), there is 1.3321 g of O for each 1.0000 g of C.

In carbon dioxide (CO₂), there is 2.6642 g of O for each 1.0000 g of C.

This demonstrates that CO₂ contains 2 times the mass of O as is contained in CO for a given mass of C.

Of all the elements in the peridic table, the vast majority are metals.  19 are nonmetals and 6 are metalloids (semimetals).

The properties of metals include luster, conductor of heat and electricity, malleable (hammered), ductile (drawn into wire). At room temperature all of the metals are solid, except mercury.

The properties of the nonmetals contrast with those of the metals.

Metalloid or semimetal can have both metallic and nonmetallic properties.  They are B, Si, Ge, As, Sb, & Te.

Br and Hg are the two elements that are liquids at room temperature.

11 elements are gases at room temperature.  H₂, He, N₂, O₂, F₂, Ne, Cl₂, Ar, Kr, Xe, Rn

7 elements exist as diatomic molecules (Brinchlhof)  Br₂, I₂, N₂, Cl₂, H₂, O₂, F₂

Allotropes are different forms of the same element that exist in the same physical state at the same temperature
and pressure.  Oxygen, O₂, and ozone ,O₃, are example of allotropes.