The Particle Theory of Matter

VA SOL PS 2a,bElements, Compounds, Mixtures

What is the smallest particle?Video hyperlink

O A piece of sand?O A bit of dust floating in the air?O What is it made of?O If it is too small for you to see, does

it still exist?O School microscope? Electron microscope?O Divide that dust into a hundred piecesO A thousand pieces? A millions pieces? O A BILLION pieces??

Sub-Atomic Particles

The AtomO The basic particle from which all

elements are madeO Elements are pure substances that

can be found on Earth. O An atom is one particle of an

elementO 92 elements occur naturally, 26 more

have been produced in science labsO Ex: oxygen, gold, sulfur

Nanoscale!

QuarksO There are particles even smaller than

atoms, but they don’t make elements – they make atoms!

O Those smaller particles areO Quarks – they have really weird names!

O Up, Down, Top, Bottom, Strange, & CharmO Leptons

O Electron, Muon, Neutrino, & Tau

ProtonO 2 up quarks and 1 down quark make a protonO Proton – the most important particle in an

atomO The number of protons in an atom determine

which element it is. Called atomic numberO 1 proton = hydrogenO 6 protons = carbonO 8 protons = oxygenO 26 protons = iron

O Has a positive electrical charge (+)

Neutron & IsotopeO 2 down quarks and 1 up quark make a neutronO Neutron – found in nucleus of atom with protonO A neutron does not have an electrical charge –

neutralO The number in a nucleus can change.

O Carbon 12 = 6 protons & 6 neutronsO Carbon 13 = 6 protons & 7 neutronsO Carbon 14 = 6 protons & 8 neutronsO Called isotopes (like flavors of ice cream)

O When they are not equal, this causes the atom to be radioactive – it breaks apart

Electron & IonO Electrons are not made of anything smaller

O Has a negative electrical charge (-)O There is usually 1 electron for every proton

O 1 proton + 1 electronO Like neutrons, that number can changeO When an atom loses or gains an electron, it is

no longer called an atom, it is now an ion.O Losing an electron makes the atom have a

positive charge (+). Its called a cation. (ACID)O Gaining an electron makes the atom have a

negative charge (-). Its called an anion. (BASE)

NucleusO Protons and neutrons are together in

the center of the atom.O It is called the nucleus

O Electrons spin rapidly around the outside of the nucleus.O They form layers – like the layers of

an onionO These layers are called “orbital

shells”

Atomic Structure

Nucleus

MoleculeO Whenever 2 or more atoms are connected,

it is called a moleculeO It can be 2 or more atoms of the same

element

OO is an atom of oxygen

OO2 is a molecule of oxygen

O Or it can be 2 or more elements of a different elementO CO2 is a molecule of carbon dioxide

CompoundO When 2 or more atoms of different

elements are hooked together, it is called a compoundO 2 atoms of hydrogen + 1 atom of oxygen =

a molecule of H2O (water)

O 1 atom of sodium + 1 atom of chlorine = a molecule of sodium chloride (NaCl or salt)

O These are chemically bonded together. They can not be physically separated

O Only a chemical reaction can break the bonds

MixtureO Mixtures are 2 or more elements or

compounds that are physically mixed togetherO They can be easily separated

O There are 2 kinds of mixturesO Heterogeneous mixtures – you can see the

different substances. Ex: Trail Mix, a salad, or a messy locker

O Homogeneous mixtures – you cannot see the different substances. Ex: Kool-Aid, milk, or air

SolutionO Solutions are a type of homogeneous

mixtureO When one substance is dissolved in

anotherO Ex: sugar dissolved in waterO Solvent – what does the dissolving

(water)O Solute – what gets dissolved (sugar)

O Water dissolves more substances than anything elseO Called the Universal Solvent

SolubilityO Solubility is a measure of how much solute

can dissolve in a solventO Ex: how much sugar can dissolve in water?O Affected by temperature

O Hotter? More sugar will dissolveO Colder? Less sugar will dissolve

O A solution is saturated when no more solute will dissolve in the solventO If hot sugar water with a LOT of sugar in it is

cooled down, then the sugar will precipitate out (fall down)