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General Biology: Chemistry and Water Basics

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이 집합의 용어 (22)

  • What is matter?

    Matter is anything with mass that takes up space.

  • Define element and atom.

    Element is a pure substance made of one type of atom. Atom is the smallest unit of an element and matter.

  • What are the three subatomic particles and their charges?

    Proton: +1 charge, ~1 amu, in nucleus.
    Neutron: 0 charge, ~1 amu, in nucleus.
    Electron: -1 charge, ~0 amu, in shells around nucleus.

  • What are the bulk elements essential for life?

    CHNOPS: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur make up ~97% of mass in organisms.

  • Difference between atomic number, mass number, and atomic mass?

    Atomic number: number of protons.
    Mass number: protons + neutrons.
    Atomic mass: average mass of all isotopes.

  • What are valence electrons and why are they important?

    Valence electrons are electrons in the outermost shell; they determine chemical bonding and reactivity.

  • Explain the octet rule.

    Atoms are most stable when their valence shell is full, usually 8 electrons in the second shell.

  • What are isotopes and radioactive isotopes?

    Isotopes have same protons but different neutrons.
    Radioactive isotopes decay, releasing energy and particles.

  • Define chemical bond, molecule, and compound.

    Chemical bond: force holding atoms together.
    Molecule: ≥2 bonded atoms.
    Compound: molecule with ≥2 different elements.

  • Difference between intramolecular and intermolecular bonds?

    Intramolecular: bonds within a molecule.
    Intermolecular: interactions between molecules.

  • What is a covalent bond and how does electronegativity affect it?

    Covalent bond: sharing electrons.
    Electronegativity difference causes nonpolar (equal sharing) or polar (unequal sharing) bonds.

  • Examples of nonpolar and polar covalent bonds?

    Nonpolar: H–H, O–O, C–H.
    Polar: H–Cl, O–H in water, N–H in ammonia.

  • What are ionic bonds and hydrogen bonds?

    Ionic bonds: attraction between oppositely charged ions.
    Hydrogen bonds: weak attraction between H and F, O, or N atoms.

  • Why is water polar and how does this affect bonding?

    Water has polar covalent O–H bonds; oxygen is partially negative (9delta^-9), hydrogens partially positive (9delta^+9), enabling hydrogen bonding between molecules.

  • List four emergent properties of water from hydrogen bonding.

    Cohesion/adhesion/surface tension, ice less dense than liquid, high specific heat and heat of vaporization, universal solvent.

  • Explain cohesion, adhesion, and surface tension in water.

    Cohesion: water sticks to water.
    Adhesion: water sticks to other polar surfaces.
    Together create surface tension.

  • Why is ice less dense than liquid water?

    Ice forms a stable hydrogen-bond lattice that spreads molecules apart, lowering density so ice floats.

  • What is specific heat and why is water's high specific heat important?

    Specific heat is heat needed to raise 1 g by 19C. Water's high value helps resist temperature changes, aiding homeostasis.

  • Define solvent, solute, and solution.

    Solvent: dissolves substances.
    Solute: dissolved substance.
    Solution: solute + solvent mixture.

  • Difference between hydrophilic and hydrophobic substances?

    Hydrophilic: water-loving, usually polar or charged, dissolves well.
    Hydrophobic: water-fearing, nonpolar, does not dissolve.

  • What is pH and how does it relate to 9[H^+]9 concentration?

    pH is a logarithmic scale measuring hydrogen ion concentration: acidic (<7, high [H^+]), neutral (=7), basic (>7, low [H^+]).

  • How do buffers maintain pH stability?

    Buffers accept or donate H^+ ions to resist pH changes, keeping biological systems near neutral pH.