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Chapter 2: General Biology: The Chemical Context of Life

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  • What is matter?

    Matter is anything that takes up space and has mass.

  • Define an element and a compound.

    An element is a substance that cannot be broken down by chemical reactions. A compound consists of two or more elements in a fixed ratio with different properties from its elements.

  • Which four elements make up 96% of living matter?

    Carbon, hydrogen, oxygen, and nitrogen make up 96% of living matter.

  • What is an atom?

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

  • Name the three main subatomic particles and their charges.

    Protons (positive), neutrons (no charge), and electrons (negative).

  • What is atomic number and atomic mass?

    Atomic number is the number of protons; atomic mass is the sum of protons and neutrons.

  • What are isotopes?

    Isotopes are atoms of the same element with different numbers of neutrons.

  • What is electronegativity?

    Electronegativity is an atom's attraction for electrons in a covalent bond.

  • Difference between nonpolar and polar covalent bonds?

    Nonpolar covalent bonds share electrons equally; polar covalent bonds share electrons unequally, causing partial charges.

  • What is a covalent bond?

    A covalent bond is the sharing of a pair of valence electrons between two atoms.

  • What is an ionic bond?

    An ionic bond is the attraction between oppositely charged ions formed by electron transfer.

  • What are cations and anions?

    Cations are positively charged ions; anions are negatively charged ions.

  • What are hydrogen bonds?

    Hydrogen bonds form when a hydrogen atom covalently bonded to one electronegative atom is attracted to another electronegative atom.

  • What are Van der Waals interactions?

    Van der Waals interactions are weak attractions between molecules due to uneven electron distribution.

  • How does molecular shape affect function?

    A molecule's shape determines how it recognizes and responds to other molecules.

  • What is the valence shell?

    The valence shell is the outermost electron shell; its electrons determine chemical behavior.

  • What is the significance of valence electrons?

    Valence electrons determine an atom's bonding capacity and chemical properties.

  • What is chemical equilibrium?

    Chemical equilibrium occurs when forward and reverse reaction rates are equal, and reactant and product concentrations remain constant.

  • What are reactants and products in a chemical reaction?

    Reactants are starting molecules; products are molecules formed by the reaction.

  • What is the role of radioactive isotopes in biology?

    Used as tracers in medicine and research to track atoms through metabolism and diagnose diseases.