Atomic Structure Review

Physical Properties of Matter

can be observed or measured without changing the sample’s composition

Extensive

depends on the amount of substance (i.e. mass, volume, length)

Intensive

independent of the amount of substance (i.e. density, odor, color, temp)

Chemical Properties of Matter

the ability or inability to change into one or more other substances

Physical Change

alters a substance without changing its composition (i.e. phase change ; solid, liquid, gas)

Chemical Change

a chemical reaction. involves a substance changing into a new substance

Heterogeneous mixture

a mixture that is not uniform (i.e. oil & vinegar)

Homogeneous Mixture

a mixture that is uniform (i.e. solutions; air)

Democritus

Matter is composed of tiny individual particles “atoms”

Aristotle

Rejected idea of atoms & empty space

Believed matter = fire, earth, air, & water

John Dalton’s Atomic Theory

Pioneered idea that all matter is made up of indivisible atoms

Atoms of a specific element are identical

Sir William Crookes Cathode Ray

Achieved groundwork for discovery of electrons

Discovered the element thallium

Millikan’s Oil Drop Experiment

Determined fundamental electric charge of a single electron & calculated its microscopic mass

Thompson’s Plum Pudding Model

Theory that atoms are balls of positive charges with little negative particles in them

Discovered electrons using cathode’s ray

Rutherford’s Model of the Atom

Experimented shooting radioactive particles at gold foil & observing deflection

Trying to prove pp model but instead proved high deflection was more likely than low deflection

Ideology of a nucleus

What is the Atomic Number?

the number of protons in an element; the identifying feature of an element

What is the Atomic Mass?

average mass of an element based on the number of protons + number of neutrons

Units = AU or AMU

Isotopes

same element, different mass

Calculate Isotope Abundance

(mass 1)(% 1) + (mass 2)(% 2) = atomic mass

Ions

Charges found on different types of elements

Cations

ions with a POSITIVE charge

Anions

ions with a NEGATIVE charge

Pure Substance

form of matter that has a constant, uniform, composition and distinct, unchanging properties; cannot be separated by physical methods (element)

Element

pure substance containing only one type of atom (i.e. U (uranium), O (oxygen), Hg (hydrogen))

Compound

pure substance containing two or more types of atoms (i.e. H20, NaCl, CH4, CO2, CO); in a compound, atoms are chemically combined and cannot be separated by physical means

Calculate Charge of an Atom

protons - electrons = charge

Mixtures

two or more elements or compounds that are NOT CHEMICALLY combined

Bonds: Molecules

non-metal + non-metal elements (i.e. CO2)

Bonds: Ions

metal + non-metal elements (i.e. NaCl)

Bonds: Metallic

metal + metal (i.e. steel alloy)

Conservation of Mass

mass is conserved in any process, such as a chemical reaction

conservation is a result of the separation, combination, or rearrangement of atoms

atoms are not created, destroyed, or divided in the process

Separation Process

1) Analyze Properties: size, density, boiling point, solubility, magnetism

2) Choose Methods: use techniques that target specific differences

3) Execute: apply methods in order, typically removing solids before liquids

Key Considerations

State of matter, Uniformity, Boiling Point, Solubility, & Particle size

Methods

Filtration (liquid + solids)

Distillation (liquids with different boiling points) - vaporizing & condensing

Evaporation (dissolved solids + liquid) - boil away liquid

Decantation (liquids with different densities)

Fully Separated Mixture

each isolated component is a pure substance showing uniform physical properties; no further separation can be achieved