Unit 1 Vocab

Observation

Observation

Knowledge about the world received through the senses of instrumentation

Fact

Something that is known to be consistent with reality

Law

A brief statement that summarizes past observations and predicts future ones

Hypothesis

A tentative interpretation or explanation that can be tested through observation

Theory

An explanation of some aspect of the natural world that has been substantiated through repeated experiments or facts gathered over time

Accurate

Value that is close to the actual “correct” value being measured

Precise

Measurement that is repeatable

Matter

Anything that has mass and takes up space

Atom

The smallest possible component of matter capable of stable existence

Element

A pure substance composed of all one type of atom

Molecule

A chemical combination of two or more elements in fixed proportions

Compound

A pure substance composed of more than one type of atom, but cannot physically be separated into different substances

Mixture

Substances which can be physically separated into different substances

Homogenous

A mixture with uniform appearance and properties throughout

Heterogenous

A mixture with physically distinguishable components

Solution

A homogenous mixture of two or more compounds

Homonuclear

Molecule composed of atoms of the same type

Heteronuclear

Molecule composed of multiple types of atoms

Monatomic

Molecule composed of one atom

Diatomic

Molecule composed of two atoms

Triatomic

Molecule composed of three atoms

Polyatomic

Molecule composed of more than three atoms

Fusion

Physical change from solid to liquid

Freezing

Physical change from liquid to solid

Vaporization

Physical change from liquid to gas

Condensation

Physical change from gas to liquid

Sublimation

Physical change from solid to gas

Deposition

Physical change from gas to solid

Law of Conservation of Mass

In a chemical reaction, matter is neither created nor destroyed

Law of Definite Proportions

All samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements

Law of Multiple Proportions

When two elements (A and B) form two different compounds, the masses of B that combine with 1 gram of A can be expressed as a ratio of small whole numbers

Cathode Ray Experiment

Determined the charge:mass ratio of electrons

Oil Drop Experiment

Determined the charge and mass of electrons

Gold Foil Experiment

Determined the location of protons in an atom

Bombardment Experiment

Determined the presence of neutrons in an atom

Proton

Subatomic particle that gives an atom its identity

Neutron

Subatomic particle that has no charge

Electron

Subatomic particle that determines the reactivity of an element

Ionic Charge

The number of protons minus the number of electrons

Isotopes

Atoms with the same number of protons but different numbers of neutrons

Mass Number

The number of protons and neutrons combined

Atomic Number

The number of protons

Periodic Law

When the elements are arranged in order of increasing atomic number, certain sets of properties recur periodically

Periods

Rows on the periodic table

Groups

Columns on the periodic table

Alkali Metal

Elements belonging to Group 1 on the periodic table

Alkaline Earth Metal

Elements belonging to group 2 on the periodic table

Halogen

Elements belonging to group 7 on the periodic table

Noble (inert) Gas

Elements belonging to group 8 on the periodic table

Electromagnetic Radiation

Oscillating electric and magnetic fields

Wavelength

Distance from one crest to the next

Frequency

Number of cycles that pass a point in a given unit of time

Period

Time it takes for a complete wave unit to pass through a point

Amplitude

Height (intensity) of a wave

Interference

Addition of wave amplitudes when the waves overlap

Diffraction

Waves bend when they encounter an obstacle that is about the same size as the wavelength

Photoelectric effect

Electrons are sometimes ejected upon irradiation of a metal surface

Work Function

The energy it takes for an electron to escape its binding energy to the atom

de Broglie Wavelength

The wavelength any matter has by virtue of its momentum

Heisenberg’s Uncertainty Principle

The position and momentum of an object cannot be known simultaneously with infinite precision

Schroödinger Equation

Describes the state (position and energy) of an atom’s electrons

Node

Where the value of a wavefunction is 0

Pauli Exclusion Principle

No two electrons in an atom may have the same set of four quantum numbers

Coulomb’s Law

Potential energy associated with the attraction and repulsion of charged particles

Shielding

Valence electrons “feel” less pull from the nucleus than core electrons do

Penetration

The possibility of high-energy electrons approaching areas closer to the nucleas

Degenerate States

States that have the same energy as each other

Core electrons

Electrons in inner “n” levels (n < n_max)

Valence electrons

Electrons in the outermost (highest) “n” level

Ground State

The configuration of electrons in which all electrons are in as low an energy orbital as possible

Excited state

Any configuration in which at least one electron is in a higher-than-baseline energy orbital

Aufbau Principle

Fill electrons from low energy to high energy

Hund’s Rule

Maximize spin alignment in degenerate orbitals and don’t pair spins unless necessary

Isoelectronic

Species containing the same electron configuration

Effective nuclear charge

The amount of protons an orbiting electron “feels”

Paramagnetic

Electron configurations with unpaired electrons

Diamagnetic

Electron configurations with no unpaired electrons

Ionization Energy

Amount of energy needed to remove an electron from an atom/ion

Electron Affinity

Amount of energy gained or released whne an atom or ion gains an electron

Pauling Electronegativity

The power of an atom in a molecule to attract electrons to itself