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Essential Chemistry Vocabulary

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By Edited Nov 13, 2013 0 0

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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