chapter 2 part 1

Atoms & Elements

  1. What is matter? → Anything with mass that takes up space.

  2. What is an atom? → Smallest individual particle of matter.

  3. How many elements exist? → 118.

  4. What elements make up ~98% of organisms? → N, C, H, O, P, S (NCHOPS).

  5. What is the atomic number? → Number of protons.

  6. Where are protons and neutrons? → Nucleus.

  7. Where are electrons? → Orbitals around the nucleus.

  8. What is atomic mass? → Protons + neutrons.

  9. What is atomic weight? → Average mass of an element's atoms, including isotopes.

  10. What is an isotope? → Same element, but with extra neutrons.

  11. What is an ion? → Atom that gained or lost electrons.

  12. What is a cation? → Positive ion; loses electrons.

  13. What is an anion? → Negative ion; gains electrons.

Nuclear vs. Chemical Reactions

  1. Nuclear fusion? → Nuclei join to form a heavier element.

  2. Nuclear fission/decay? → Unstable nucleus splits into smaller atoms.

  3. Chemical reaction? → Electrons move without changing the nucleus.

Molecules & Bonds

  1. What is a molecule? → 2+ chemically bonded atoms.

  2. What is a compound? → Molecule made of 2+ different elements.

  3. What is the valence shell? → Outermost electron shell.

  4. What are valence electrons? → Electrons in the outer shell.

  5. What is electronegativity? → Ability to attract electrons.

  6. What is an ionic bond? → Electrons are transferred.

  7. What is a covalent bond? → Electrons are shared.

  8. What is a polar covalent bond? → Electrons are shared unequally.

  9. What is a nonpolar covalent bond? → Electrons are shared equally.

  10. What is a cation + anion attraction? → Ionic bond.

  11. What makes covalent bonds stronger? → More shared electron pairs.

  12. Single/double/triple bonds contain how many electrons? → 2 / 4 / 6.

Hydrogen Bonds & Water

  1. What is a hydrogen bond? → Weak attraction between polar molecules.

  2. Why is water polar? → Oxygen attracts electrons more strongly than hydrogen.

  3. What is cohesion? → Water sticking to water.

  4. What is adhesion? → Water sticking to other surfaces.

  5. What causes water's surface tension? → Cohesion/H-bonds.

  6. Why does ice float? → Ice is less dense than liquid water.

  7. What is a solution? → Mixture where substances are evenly distributed.

  8. What is a solvent? → Substance that does the dissolving.

  9. What is a solute? → Substance being dissolved.

  10. What does "likes dissolve likes" mean? → Polar dissolves polar; nonpolar dissolves nonpolar.

  11. What is hydrophilic? → Water-loving; usually polar/charged.

  12. What is hydrophobic? → Water-repelling; usually nonpolar.

  13. What is specific heat? → Heat needed to raise a substance 1°C.

  14. Why does evaporation cool surfaces? → Evaporation requires lots of heat energy.

pH

  1. What does pH measure? → H⁺ concentration.

  2. What is an acid? → Increases H⁺.

  3. What is a base? → Increases OH⁻/decreases H⁺.

  4. pH scale? → 0–14.

  5. Neutral pH? → 7.

  6. Acidic pH? → Below 7.

  7. Basic pH? → Above 7.

  8. What happens to H⁺ when pH decreases? → Increases.

  9. What happens to H⁺ when pH increases? → Decreases.

  10. What happens with a 1-point pH change? → 10× change in H⁺.

  11. What is a buffer? → Helps prevent large pH changes.

  12. What pH do organisms generally function around? → 7.0–7.4.