chapter 2 part 1

What is matter?

Anything with mass that takes up space.

What is an atom?

Smallest individual particle of matter.

How many elements exist?

118.

What elements make up ~98% of organisms?

N, C, H, O, P, S (NCHOPS).

What is the atomic number?

Number of protons.

Where are protons and neutrons?

Nucleus.

Where are electrons?

Orbitals around the nucleus.

What is atomic mass?

Protons + neutrons.

What is atomic weight?

Average mass of an element's atoms, including isotopes.

What is an isotope?

Same element, but with extra neutrons.

What is an ion?

Atom that gained or lost electrons.

What is a cation?

Positive ion; loses electrons.

What is an anion?

Negative ion; gains electrons.

What is nuclear fusion?

Nuclei join to form a heavier element.

What is nuclear fission/decay?

Unstable nucleus splits into smaller atoms.

What is a chemical reaction?

Electrons move without changing the nucleus.

What is a molecule?

2+ chemically bonded atoms.

What is a compound?

Molecule made of 2+ different elements.

What is the valence shell?

Outermost electron shell.

What are valence electrons?

Electrons in the outer shell.

What is electronegativity?

Ability to attract electrons.

What is an ionic bond?

Electrons are transferred.

What is a covalent bond?

Electrons are shared.

What is a polar covalent bond?

Electrons are shared unequally.

What is a nonpolar covalent bond?

Electrons are shared equally.

What is a cation + anion attraction?

Ionic bond.

What makes covalent bonds stronger?

More shared electron pairs.

How many electrons are involved in single/double/triple bonds?

2 / 4 / 6.

What is a hydrogen bond?

Weak attraction between polar molecules.

Why is water polar?

Oxygen attracts electrons more strongly than hydrogen.

What is cohesion?

Water sticking to water.

What is adhesion?

Water sticking to other surfaces.

What causes water's surface tension?

Cohesion/H-bonds.

Why does ice float?

Ice is less dense than liquid water.

What is a solution?

Mixture where substances are evenly distributed.

What is a solvent?

Substance that does the dissolving.

What is a solute?

Substance being dissolved.

What does 'likes dissolve likes' mean?

Polar dissolves polar; nonpolar dissolves nonpolar.

What is hydrophilic?

Water-loving; usually polar/charged.

What is hydrophobic?

Water-repelling; usually nonpolar.

What is specific heat?

Heat needed to raise a substance 1°C.

Why does evaporation cool surfaces?

Evaporation requires lots of heat energy.

What does pH measure?

H⁺ concentration.

What is an acid?

Increases H⁺.

What is a base?

Increases OH⁻/decreases H⁺.

What is the pH scale?

0–14.

What is neutral pH?

7.

What is acidic pH?

Below 7.

What is basic pH?

Above 7.

What happens to H⁺ when pH decreases?

Increases.

What happens to H⁺ when pH increases?

Decreases.

What happens with a 1-point pH change?

10× change in H⁺.

What is a buffer?

Helps prevent large pH changes.

What pH do organisms generally function around?

7.0–7.4.