Biology - Chemistry Review (Chapter 2)

Vocabulary flashcards covering key terms and concepts from the lecture notes on atoms, bonding, periodic table, water properties, and acids/bases.

Atom

Smallest part of an element that displays the properties of that element; made up of protons, neutrons, and electrons.

Proton

Positively charged subatomic particle located in the nucleus.

Neutron

Electrically neutral subatomic particle located in the nucleus.

Electron

Negatively charged subatomic particle that orbits the nucleus.

Element

A substance that cannot be broken down into simpler substances by ordinary chemical means.

Matter

Anything that takes up space and has mass.

Phases of Matter

Solid, liquid, and gas—the three distinct states of matter.

Periodic Table

A table of the elements organized by properties, showing atomic number, symbol, name, and atomic mass.

Atomic Number

Number of protons in an atom’s nucleus.

Symbol

Abbreviation or shorthand notation for an element (e.g., H, Si).

Atomic Mass

Mass of an atom, usually measured in atomic mass units (amu); weighted average for an element.

Mass Number

Sum of protons and neutrons in an atom; shown as a superscript to the upper left of the symbol.

Isotopes

Atoms of the same element with different numbers of neutrons.

Radioactive Isotopes

Isotopes that release energy as they decay. Used in medicine and research.

Ion

An atom with a net electric charge due to loss or gain of electrons.

Octet Rule

The outer electron shell is most stable when it contains eight electrons.

Valence Electrons

Outer-shell electrons involved in chemical bonding and an element’s reactivity.

Ionic Bonds

Bonds formed by transfer of electrons, creating charged ions.

Covalent Bonds

Bonds formed by sharing a pair of electrons between atoms.

Polar Covalent Bonds

Covalent bonds where electrons are shared unequally due to differing electronegativities.

Hydrogen Bonds

Weak bonds where a hydrogen atom in one molecule is attracted to an electronegative atom in another; not sharing electrons.

Electronegativity

Attraction of an atom for electrons in a covalent bond; more protons usually mean stronger attraction.

Polar Molecule

A molecule with an uneven distribution of charge due to polar bonds (e.g., water).

Water

A polar molecule that forms hydrogen bonds, is a solvent, and exhibits cohesion, adhesion, and surface tension.

Solvent

A substance that dissolves solutes to form a solution.

Solute

Substance dissolved in a solvent.

Solution

A uniform mixture of solute and solvent.

Cohesion

Attraction between like molecules (e.g., water–water).

Adhesion

Attraction between unlike molecules (e.g., water to a surface).

Surface Tension

Tension at the surface of a liquid caused by cohesive forces among surface molecules.

Density of Ice vs Water

Ice is less dense than liquid water, so it floats.

pH

A measure of how acidic or basic (alkaline) a solution is, on a scale from 0 to 14.

Acids

Substances that release hydrogen ions (H+) in water; examples include HCl.

Bases

Substances that release hydroxide ions (OH-) or accept H+ in water; examples include NaOH.

Buffer

A system that helps maintain pH within a narrow range, such as blood.

Carbonic Acid (H2CO3)

Weak acid formed when carbon dioxide dissolves in water; dissociates to H+ and HCO3-. Controlling blood pH.

H+ Ions

Hydrogen ions; determine acidity of a solution.

OH- Ions

Hydroxide ions; determine basicity of a solution.

Neutral

pH of 7; [H+] equals [OH-].

Molecular Formula

Notation showing the number and type of atoms in a molecule (e.g., H2O).

Structural Formula

Notation that shows the arrangement of atoms and bonds in a molecule.