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Introduction to Chemistry

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Terms in this set (20)

  • What is a chemical element?

    A pure substance that cannot be broken down further and contains only one type of atom.

  • Describe the structure of an atom.

    An atom consists of a nucleus containing protons (+ charge) and neutrons (neutral), surrounded by electrons (- charge) orbiting in shells.

  • What determines the atomic number of an element?

    The number of protons in the nucleus of an atom.

  • What is the difference between an atom and an ion?

    An atom is electrically neutral, while an ion is charged due to loss or gain of electrons.

  • Define cation and anion.

    Cation: positively charged ion (lost electrons).
    Anion: negatively charged ion (gained electrons).

  • How are electrons arranged in an atom?

    Electrons orbit in electron shells with specific capacities: 1st shell = 2, 2nd shell = 8, 3rd shell = 8 electrons.

  • What is the valence shell?

    The outermost electron shell of an atom, which determines chemical reactivity.

  • What makes an atom chemically reactive or inert?

    Atoms with filled valence shells are inert; those with unfilled valence shells are reactive.

  • What is an ionic bond?

    A chemical bond formed by the transfer of electrons from one atom to another, creating oppositely charged ions that attract.

  • What is a covalent bond?

    A chemical bond formed when atoms share one or more pairs of electrons to fill their valence shells.

  • How is a water molecule formed?

    By covalent bonds between one oxygen atom and two hydrogen atoms sharing electrons.

  • Why is water a polar molecule?

    Because oxygen is more electronegative than hydrogen, it attracts shared electrons more strongly, creating partial charges.

  • What is electronegativity?

    The attraction an atom has for shared electrons in a covalent bond.

  • What is a hydrogen bond?

    An attraction between the slightly positive hydrogen pole of one polar molecule and the slightly negative pole of another.

  • How do hydrogen bonds differ from ionic and covalent bonds?

    Hydrogen bonds are weaker intermolecular attractions, not bonds formed by electron transfer or sharing.

  • What role do hydrogen bonds play in large molecules?

    They help hold large molecules like proteins and DNA together by stabilizing their structure.

  • What is the significance of chemical bonds in molecules?

    Chemical bonds hold atoms together to form molecules, achieving stability in valence electron shells.

  • What is the relationship between atoms, cells, tissues, and organs?

    Atoms combine to form molecules, which build cells; similar cells form tissues, and tissues combine to form organs.

  • What is the atomic mass unit (amu) of protons, neutrons, and electrons?

    Protons and neutrons each have a mass of about 1 amu, electrons have negligible mass (~0 amu).

  • How do atoms achieve stability through bonding?

    By filling their valence electron shells through sharing (covalent) or transferring (ionic) electrons.