Matter

MatterMixtures a combination of substances in which each substance retains its individual properties

Heterogeneous mixtures mixtures that do not blend evenly throughout

Homogenous mixtures have a constant composition (also known as solutions)

Types of solutionsSystemExampleGas gasAir is primarily a mixture of nitrogen, oxygen and argon gasesGas liquidCarbonated beverages contain carbon dioxide gas in solutionLiquid gasMoist air contains water droplets in airLiquid liquidVinegar contains acetic acid and waterSolid liquidSweetened powder drink contains sugar and other solid ingredients in water.Solid solidSteel is an alloy of iron containing carbonSeparating MixturesFiltration a technique that uses a porous barrier to separate a solid from a liquid

Distillation a separation technique based on the boiling points of the substances involved

Crystallization is a separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance

Chromatography is a technique that separates the components of a mixture on the basis of the tendency of each to travel across the surface of another

ElementsAn element is a pure substance that cannot be separated into simpler substances

Only 91 of the elements occur naturally

Each element has its own chemical name and symbolThe elements are found on the Periodic Table of Elements

Dmitri Mendeleev revolutionized the periodic table by setting it up into rows and columns

Many scientists have contributed to the set up we use today

Compound a combination of two or more elements that are combined chemically

When two or more elements combine to form a compound they lose their individual properties, and have a new set of properties

Example: table salt is made of sodium and chlorineSodium is a metal Chlorine is a poisonous gasTogether, sodium chloride, is a white crystal substance safe to eatLaw of definite ProportionsThis law says that the elements that form compounds, combine in definite proportions.

Regardless of amount, a compound is always composed of the same elements in the same proportions by massPercent by MassShows the ratio of the mass of each element to the total mass of the compound

Percent by mass = mass of element x 100 mass of compoundLaw of Multiple ProportionsDifferent compounds are formed by a combination of the same elements

H2O2 and H2O

Ratio of oxygen is 2:1Early Theories and Ideas of AtomsDemocrituss Ideas of an Atom- Matter is composed of empty space through which atoms moveAtoms are solid, homogeneous, indestructible and indivisibleDifferent types of atoms have different sizes

Democritus ideas were just ideas NOT science. He was ahead of his time in his thinking.Daltons Atomic Theory-All matter is composed of small particles called atomsAll atoms of a specific atom are identical, having the same mass, size and shape.Atoms of a specific element are different from those of other elementsAtoms cannot be created or dividedDifferent atoms combine to form compoundsIn a chemical reaction, atoms are separated, combined or rearranged

`Research continued and proved some of Daltons theory to be wrong

Scientist accidently discovered something known as the cathode ray.

The cathode ray is a tube where radiation strikes a coating that produces a light

The discovery of the cathode ray has led to the invention of the television

The cathode ray tube led scientist to discover negative charged particles

JJ Thomson used the cathode ray tube to continue research on atoms

He discovered that there are particles smaller then the atom, meaning atoms can divide into smaller subatomic particles.

Thomson had identified the first subatomic particles: the electronRobert Millikan determined that electrons were negative and have a mass of about 9.1 x 10-28 gJJ Thomsons atomic theory is known as the Plum Pudding Model

He described it as the negative charges are like plums embedded into a positive pudding

JJ Thomsons Atomic Theory Thomson knew that atoms had smaller particles that were called electrons and were negativeHe also knew that all matter is neutral in chargeHe created a model that would support these, it was called the plum pudding modelA modern day name could be a chocolate chip cookie dough model.

And the research continues.Ernest Rutherford became curious about positively charged alpha particles and how they interacted with solid matter

Rutherford and a few other scientists designed an experiment to see how alpha particles would act when aimed at a thin sheet of gold foilA ray of alpha particles was beamed at a thin piece of gold foil

A zinc sulfide coated screen surrounded the gold foil produced a flash whenever an alpha particle struck it

By seeing the flashes they would be able to see if the gold foil deflected the particlesRutherford believed that the particles would just pass through the foil with little deflection

However, several particles deflected back at large angles, some even right back to the source

Rutherford and his scientist were amazed, he said it would be similar to firing a large artillery shell at a sheet of paper and having the shell come back and hit youRutherford made these conclusions from his experiment:Atoms consist of mostly empty spaceTiny dense region centrally located in the atom, nucleus, that contained positive charge and all of its massElectrons move through the empty space around the nucleus.8 years after the Gold Foil Experiment Rutherford concluded that the positively charge nucleus contained particles called protons

In 1932 James Chadwick showed that an atom contained a third subatomic particle. The neutron, located in the nucleus, is neutrally chargedProtons, neutrons and electrons are the 3 subatomic particles that make up an atom

Niels Bohrs Atomic Theory There is a positively charged nucleusElectrons orbit the nucleus similar to the planets in the solar systemElectrons are in orbitalsEach orbital has an energy associated with it

Electron Cloud ModelThe electron cloud model was formed based on the previous models and contributions from many scientist.Nucleus contains protons and neutronsElectrons are outside the nucleusElectron movement is described by regions with fuzzy boundaries causing a cloud.