Essential Chemistry Vocabulary
Chemistry – Study of matter's properties composition, structure and changes
Chemical – A substance with definite composition
Mass – Amount of matter in an object, Unit: Gram, Measured with: Balance
Weight – Measure of gravitational force an object has on another, Unit: Newton/Dyne, Measured with- Spring scale
Matter – Anything with mass that occupies 3-dimensional space
Atom – The smallest particle of an element that retains all chemical properties of that element
Element – A pure substance made of only one kind of atom
Compound – A pure substance composed of two or more elements chemically combined
Molecule – A group of atoms linked together by covalent bonds
Extensive Property – A property that depends on the quantity of matter present
Intensive Property – A property that does not depend on the quantity of matter present
Physical Property – A property that doesn't relate to changing a substances identity
Chemical Property – A property relating to a substances ability to undergo chemical change
Solid – A state of matter where the elements move slowly and vibrate around fixed points that has a structured molecular composition, and has definite volume and shape.
Liquid – A state of matter where the elements are close, but free to move quickly about, unstructured molecular composition implies definite volume, but indefinite shape
Gas – A state of matter where elements move very fast and are highly distant from other particles, bonds between elements are weak, indefinite volume and shape
Vapor – Gaseous form of a substance that is naturally in a liquid or solid state
Reactants – Elements taking place in a chemical reaction
Products – Result of a chemical reaction
Mixture – Two or more kinds of matter that can be separated, each retains it's own properties
Homogeneous – Mixtures uniform in composition
Heterogeneous- Mixtures not uniform in composition
Pure Substance – Substance that cannot be broken down by chemical means, has a fixed composition
Group or Family – Vertical columns on periodic table, similar characteristics and properties
Period or Series – Rows on periodic table
Metal – Elements that are good conductors of electricity, they have luster, are malleable, ductile and electropositive.
Non-Metal – Elements that are bad conductors of electricity, they are dull, hard, brittle, and electronegative.
Nobel Gas – Group 18 gases that do not react
Halogen
– Highly reactive group of non-metals at group 17 of periodic table
Scientific Method – Logical approach to solving problems by observation, formulating a question, researching and collecting data, forming a hypothesis, testing, and conclusion
System – A specific portion of matter in a given region of space that has been selected for study during an experiment or observation
Hypothesis – Testable statement or educated guess supported by data but not widely accepted as truth
Model – An explanation of how phenomena occur and how data and events are related
Theory – Broad generalization that explains a body of facts or phenomena, attempts to explain 'what' happened, generally regarded as true
Scientific Law – Specific explanation explaining how phenomena occur that are theoretically proven throughly
Quantity – Something with magnitude, size or amount
Weight – The measure of the force of gravitational attraction another object has on that object
Length – Linear distance between two points
Volume – Amount of three-dimensional space occupied by an object
Density – Ration of mass to volume
Conversion Factor – Ratio used to convert between two units
Accuracy – Closeness of measurements to the accepted value
Precision – Closeness of a set of measurements made in the same way
Percent Error – A difference in percent between a measurement to the accepted value
Significant Figures – All known digits plus a final digit which is uncertain or guessed
Scientific Notation – Numbers are written in form M X 10n where 1≤m<10 and n is an integer
Direct Proportionality – Dividing one quantity by another gives a constant value, and the two quantities increase together
Inverse Proportionality – The product of two quantities is constant, one quantity increases while the other decreases.
Law of conservation of mass – Mass is neither created nor destroyed during ordinary chemical reactions or physical changes
Law of definate proportions- Chemical compounds have the same elements in the same proportions regardless of size of the sample
Law of multiple proportions – If two or more elements combined in more than one way and the mass of one element is held constant, then the masses of the other elements will be in a ration of small whole numbers
Dalton's Atomic Theory – All mater is composed of elements, Atoms of the same element are (chemically) the same, and atoms of different elements are (chemically) different, Atoms can't be subdivided, created or destroyed (by ordinary means) Atoms bond in whole number ratios to form compounds, In chemical reactions, atoms are combined, separated, or rearranged. ( ) = modern theory
Atom – The smallest particle of an element that retains the properties of that element
Electron – Negative subatomic particle orbiting around the nucleus
Nucleus – Central portion of an element containing protons and neutrons
Proton – Positive subatomic particle in the nucleus
Neutron – Neutral subatomic particle in the nucleus.
Nuclear Forces – Strong force holds subatomic particles together at extremely small distances, and weak force deals with radioactivity
Atomic Number – The number of protons in the nucleus of every atom of that element
Isotopes – Atoms of the same element with a different number of neutrons
Nuclide
– Any isotope of any element
Atomic Mass Unit – 1/12 of the mass of a carbon- 12 atom
Mole – Mass in grams of the Avogadro number quantity of any chemical unit
Avogadro's Number – 6.03X10^23
Molar Mass – The mass of one mole of a pure substance (in grams)
Electromagnetic Radiation – A form of energy that exhibits wavelike behavior as it travels through space
Electromagnetic Spectrum – All the forms of electromagnetic radiation
Wavelength – The distance between corresponding points on adjacent waves λ
Frequency – The number of waves that pass a given point in a specific time (usually one second)
Hertz – The SI unit for frequency
Photoelectric effect – The emission of electrons from a metal when light shines on the metal
Quantum – The minimum quantity of energy that can be lost or gained by an atom
Photon – A particle of electromagnetic radiation having zero mass and carrying a quantum of energy
Ground State – The lowest energy state of an atom
Heisenberg uncertainty principle – It is impossible to subsequently determine the velocity and position of an electron or any other particle
Quantum Theory – Describes mathematically the wave properties of electrons and other very small particles
Quantum Number – Specifies the properties of atomic orbitals and the properties of electrons in orbitals
Principle quantum number – n; indicates the main energy level occupied by the electron
Angular momentum quantum number – l; shape of orbital
Magnetic Quantum number – m; Orientation in space of a given orbital
Spin quantum number - +/- 1/2 spin which indicates the two fundamental states of an electron in an orbital
Electron Configuration – Arrangements of electrons in an atom
Aufbau Principle – An electron occupies the lowest energy orbital that can receive it
Pauli Exclusion principle – no two electrons in the same atom can have the same set of four quantum numbers
Hund's rule – Orbitals of equal energy must each have an electron spinning in the same direction before they can occupy another electron
Orbital notation – ØØ < That way of expressing electron configuration
Electron configuration – 1s2 2s1 < That way of expressing electron configuration
Highest occupied level – The electron-containing main energy level with the highest principle quantum number
Inner-shell electrons – Electrons not in the highest occupied energy level
Noble gases – Nonreactive group 18 elements with no valence electrons meaning the p orbital is filled and the highest (p) orbital has an 'octet' of electrons
Noble gas configuration - [Ar]2s1 < That way of expressing electron configuration
Periodic law- If elements are arranged in order of increasing atomic number, there is a periodic repetition of chemical and physical properties.
Periodic Table – Arrangement of elements demonstrated on a table
Noble Gas – Group 18, Non-Reactive
Lanthanide – Upper row of rare earth elements
Actinide – Lower row of rare earth elelments
Alkali Metals – Group 1
Alkaline Earth Metals – Group 2
Transition Elements- Group 21-30 of the periodic table, D group
Main Group Elements – P Block and F Block (Everything but rare earth and transition elements)
Halogens – Group 17, Highly reactive
Atomic Radius – How big an atom is
Ionization energy – How much energy required to remove one electron from a neutral atom
Electron Affinity – The energy change that occurs when an electron is aquired by a neutral atom.
Cation – Positively charged ion formed when an atom loses an electron
Anion – Negatively Charged ion formed when an atom gains an electron
Valence Electron – Electrons in an incomplete outer shell
Electronegativity – Measure of the attraction that an atom has for electrons being shared between it an another atom
Chemical Bond – Mutual electrical attraction between the nuclei and valence electrons of different atoms.
Ionic Bonding – A transfer of one or more electrons from one atom to another
Covalent Bonding – Atoms share electron pairs
Polar Covalent Bond – A covalent bond with an uneven sharing of electrons
Molecule – The smallest particle of a compound that is bonded covalently
Molecular compound – A chemical compound whose simplest units are molecules
Chemical formula – Shorthand way of representing the composition of a sustance using symbols and subscripts
Diatomic Molecule – A molecule containing only two atoms
Bond Length – Distance between two bonded atoms at minimum potential energy
Bond Energy – Energy Required to break a chemical bond
Octet Rule – Chemical compounds tend to form so each atom has an octet of eight electrons by gaining, loseing, or sharing electrons
Unshared pair – A pair of electrons not involved in bonding, belong exclusively to one atom
Structural Formula – Shows kind, number, arrangement, and bonds but not unshared pairs of the atoms in a molecule
Single Bond – A covalent bond produced by the sharing of one pair of electrons between two atoms
Double Bond - A covalent bond produced by the sharing of two pairs of electrons between two atoms
Triple Bond - A covalent bond produced by the sharing of three pairs of electrons between two atoms
Resonance – Bonding in molecules and ions that cannot be represented by a single lewis structure, bonds switch/vary
Ionic Compound – Compound composed of positive and negative charged ions, whose opposite charges attract, and balance each other out.
Formula Unit – The simplist collection of atoms from which an ionic compound's formula is formed
Lattice Energy – The energy released when one mole of an ionic compound is formed from gaseous ions
Polyatomic Ion – A charged group of covalently bonded atoms that act as a single particle when reacting.
Metallic Bonding – Type of chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons
Malleable – Able to be shaped
Ductile – Able to be made into thin wire
Molecular polarity – Uneven distribution of molecular charge
VSEPR theroy – The sets of valence electrons will be as far away from each other due to repulsion between the sets.
Hybridization – The mixing of two or more atomic orbitals of similar energies on the same atom to produce new orbitals of equal energies
Hybrid Orbitals – Orbitals of equal energy produced by the combination of two or more orbitals on the same atom
Intermollecular forces – Forces of attraction between molecules
Dipole-Dipole Forces – Force of attraction between opposite ends of polar molecules
Hydrogen Bonding – When hydrogen in a polar molecule is attracted to a very electronegative element in a second polar molecule
Monatomic Ion – Ion fomed from a single atom
Binary Compound – Compound existing of two elements
Nomenclature – Naming System
Oxyanion – Negatively charged polyatomic ion containing oxygen and at least one other element
Salt – An ionic compound composed of a cation from a base and an anion from an acid
Oxidation Number – A signed number indicating the number of electrons assumed to be gained or lost by an atom when forming a compound
Formula Mass – The sum of the average atomic masses of all the atoms represented in its formula
Empirical formula – Smallest whole number ratio formula
Chemical Equation – Represents with symbols and formulas the identities and relative amounts of the reactions and products in a chemical reaction
Precipitate – A solid that is produced as a result of a chemical reaction in solution and that separates
Coefficient – A number written before a formula in chemical equations
Synthesis Reaction – Two products forming one reactant A+B=AB
Decomposition Reaction – One product forming multiple reactants AB=A+B
Electrolysis – Decomposition of a substance by an electric current
Single Replacement Reaction – One substance replaces another in a compound A+BX=AX+B
Double Replacement Reaction – The ions of two compounds exchange places AX+BY=AX+BY
Combustion Reaction – A substance combines with oxygen releasing a large amount of energy in the form of light and heat.
Stoichiometry – Chemistry involving mass relationships
Limiting Reactant- The reactant that limits the amounts of the other reactants that can combine and the amount of product that can form in a chemical reaction.
Percent Yield – The ratio of actual yeild to the theoretical yeild, multiplied by 100
Ideal Gas – Imaginary gas that perfectly fits all assumptions of the kinetic molecular theory.
Fluid – A substance that can flow and take the shape of it's container
Diffusion – Spontaneous mixing of the particles of two substnaces caused by their random motion.
Effusion – A process by which
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