Basic Chemistry

Buffer

A buffer is a chemical or a combination of chemicals that keeps pH within normal limits. Many commercial products such as shampoos or deodorants are buffered.

Hydrogen Bond

A hydrogen bond is the attraction of a slightly positive hydrogen to a slightly negative atom in the vicinity.

Molecule

A molecule exists when two or more elements bond together. It is the smallest part of a compound that retains its chemical properties.

Solution

A solution contains dissolved substances, which are then called solutes.

Solvent

A substance that dissolves a solute (a chemically different liquid, solid or gas), resulting in a solution. Due to its polarity, water facilitates chemical reactions. As a solvent, it dissolves a great number of substances, especially those that are also polar.

Acid

Acids are substances that dissociate in water, releasing hydrogen ions [H+). T The acidity of a substance depends on how fully it dissociates in water.

Element

All matter is composed of certain basic substances called elements. An element cannot be broken down to simpler substances with different properties by ordinary chemical means. There are only 92 naturally occurring elements that serve as the building blocks of matter.

Atom

An Atom is the smallest part of an element that displays the properties of the element. An element and its atoms share the same name. One or two letters create the atomic symbol, which stands for this name. Atoms are formed by subatomic particles called protons, neutrons and electrons. Protons and neutrons residing in the nucleus, and the electrons in surrounding orbitals.

Valence Electron

An electron that is associated with an atom, and that can participate in the formation of a chemical bond; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair.

Ion

Atom or molecule in which the total number of electrons is not equal to the total number of protons, giving the atom a net positive or negative electrical charge.

Base

Bases are substances that either take up hydrogen ions (H+) or release hydroxide ions [0H~).

Cohesion

Cohesion refers to the ability of water molecules to cling to each other due to hydrogen bonding. ;. Because of cohesion, water exists as a liquid under the conditions of temperature and pressure present at the Earth's surface.

Electrolyte

Electrolytes are liquid substances that act as a medium to conduct electricity. Electrolytes ionize when dissolved in suitable ionizing solvents such as water.

Ionic Bond

Ionic compounds are held together by a strong attraction between negatively and positively charged ions called an ionic bond.

Isotope/Radioisotope

Isotopes are atoms of the same element that differ in the number of neutrons. Isotopes have the same number of protons, but they have different atomic masses. An Isotope that decays releases various types of energy in the form of rays and subatomic particles, and therefore it is termed a radioactive isotope.

Matter

Matter refers to anything that takes up space and has mass. It only exists in three distinct states: solid, liquid, or gas.

Hydrophilic

Molecules that can attract water are said to be hydrophilic.

Hydrophobic

Nonionized and nonpolar molecules that cannot attract water.

Covalent Bond

Results when two atoms share electrons in such a way that each atom has an octet of electrons in the outer shell [or two electrons, in the case of hydrogen).

Salt

Solid substance that usually separates and exists as individual ions in water.

Law of conservation of mass

States that in a chemical reaction , the mass of the products equals the mass of the reactants .

Neutron

Subatomic particle having no charge, mass slightly greater than that of a proton, Located within the nucleus of all atoms except those of hydrogen.

Electron

Subatomic particle with a negative electric charge that is equal, but opposite to, the positive charge of a proton. Electrons move about the nucleus.

Mass Number

Sum of protons and neutrons in the nucleus of an atom. Protons and neutrons are assigned one atomic mass unit (AMU) each. Electrons are so small that their AMU is considered zero in most calculations.

Solute

The dissolved substance in a solution.

Group Number

The group number is an identifier used to describe the column of the standard periodic table in which the element appears.Groups 1-2 (except hydrogen) and 13-18 are termed main group elements.Groups 3-11 are termed transition elements.

Atomic Number

The number of protons in the nucleus of an atom is referred to as its atomic number. All atoms of an element have the same number of protons housed in the nucleus.

Proton

The proton is a subatomic particle with a positive electric charge of 1 elementary charge and mass slightly less than that of a neutron. One or more protons are present in the nucleus of an atom.

Half Life

The time period during which half of the atom of a radioactive element undergoes a nuclear process to be reduced into a lighter element

Polar Covalent Bond

When electrons are not shared equally, the covalent bond is a polar covalent bond.

Nonpolar covalent bond

When the sharing of electrons between two atoms is equal, the covalent bond is said to be a nonpolar covalent bond.

pH

pH is a measure of how acidic or basic a substance is. If the solution has an equal amount of acidic and alkaline molecules, the pH is considered neutral.