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General Biology: Basic Chemistry Concepts

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  • Matter

    Matter is anything that takes up space and has mass.

  • Element

    An element is a substance that cannot be broken down into other substances by chemical reactions.

  • Atom

    An atom is the smallest unit of matter that retains the properties of an element.

  • Protons

    Protons are subatomic particles with a positive charge, found in the nucleus, with a mass of about 1.7Ɨ10āˆ’24 g.

  • Neutrons

    Neutrons are neutral subatomic particles in the nucleus with a mass about 1.7Ɨ10āˆ’24 g.

  • Electrons

    Electrons are negatively charged subatomic particles with a mass about 1/2000 that of a proton, moving around the nucleus.

  • Atomic number

    The atomic number is the number of protons in an atom's nucleus, unique to each element.

  • Atomic mass

    Atomic mass is the total mass of an atom, averaged for isotopes weighted by abundance, and equals the mass in grams of 1 mole of the atom.

  • Isotope

    An isotope is an atomic form of an element with the same number of protons but different numbers of neutrons.

  • Ion

    An ion is an atom or group of atoms that has gained or lost electrons, acquiring a charge.

  • Molecule

    A molecule consists of two or more atoms held together by covalent bonds.

  • Compound

    A compound is a substance made of two or more different elements combined in a fixed ratio.

  • Chemical bond

    A chemical bond is an attraction between atoms due to sharing electrons or opposite charges, resulting in complete outer electron shells.

  • Ionic bond

    An ionic bond forms from the attraction between oppositely charged ions.

  • Covalent bond

    A covalent bond is a strong bond where two atoms share one or more pairs of valence electrons.

  • Nonpolar molecule

    A nonpolar molecule shares electrons equally, resulting in no electrical charges or poles.

  • Polar molecule

    A polar molecule has an uneven distribution of charges, like water.

  • Hydrogen bonds

    Hydrogen bonds are weak bonds where a slightly positive hydrogen atom is attracted to a slightly negative atom in another molecule or region.

  • Hydrophobic interactions

    Hydrophobic interactions occur when molecules that do not mix with water cluster together to exclude water.

  • pH

    pH measures the acidity or alkalinity of a solution.

  • Acids

    Acids increase the hydrogen ion concentration of a solution.

  • Bases

    Bases reduce the hydrogen ion concentration of a solution.

  • Salts

    Salts are compounds formed by ionic bonds, also called ionic compounds.

  • Buffers

    Buffers are solutions containing a weak acid and its base that minimize pH changes when acids or bases are added.