Basic Chemistry (Chapter 2)

What are matter, mass, and weight?

Matter has mass and occupies space. Mass is the amount of matter, while weight is the effect of gravity on mass.

What is energy, and how do kinetic and potential energy differ?

Energy is the capacity to do work or move matter. Kinetic energy is active energy; potential energy is stored energy.

What are the four main forms of energy?

Chemical energy is stored in bonds; electrical energy comes from charged particles; mechanical energy moves matter; radiant energy travels in electromagnetic waves.

How do solids, liquids, and gases differ?

Solids have definite shape and volume. Liquids have changeable shape but definite volume. Gases have changeable shape and volume.

What are an element, atom, and atomic symbol?

An element cannot be chemically broken into simpler substances. An atom is its smallest particle. An atomic symbol is its one- or two-letter abbreviation.

Which four elements make up about 96% of the body?

Oxygen 65%, carbon 18.5%, hydrogen 9.5%, and nitrogen 3.2%.

Which elements are considered lesser and trace elements in the body?

Lesser: Ca, P, K, S, Na, Cl, Mg, I, and Fe. Trace: Cr, Co, Cu, F, Mn, Mo, Se, Si, Sn, V, and Zn.

What are the symbols for oxygen, carbon, hydrogen, nitrogen, and calcium?

Oxygen = O; carbon = C; hydrogen = H; nitrogen = N; calcium = Ca.

What are the symbols for phosphorus, potassium, sodium, chlorine, sulfur, iron, and iodine?

Phosphorus = P; potassium = K; sodium = Na; chlorine = Cl; sulfur = S; iron = Fe; iodine = I.

What are the formulas for carbon dioxide, carbon monoxide, water, and table salt?

Carbon dioxide = CO2; carbon monoxide = CO; water = H2O; table salt = NaCl. Capitalization matters.

What are the charges, masses, and locations of the three subatomic particles?

Protons are positive, about 1 amu, and in the nucleus. Neutrons are neutral, about 1 amu, and in the nucleus. Electrons are negative, nearly 0 amu, and occupy shells.

What determine an atom’s electrical neutrality, atomic number, and mass number?

A neutral atom has equal protons and electrons. Atomic number equals protons. Mass number equals protons plus neutrons.

What are isotopes, atomic weight, and radioisotopes?

Isotopes have the same number of protons but different neutrons. Atomic weight reflects the average isotope mass. Radioisotopes are unstable isotopes that release radiation.

What are electron shells, the valence shell, and the octet rule?

Electrons occupy energy shells. The valence shell is outermost and participates in reactions. Most atoms seek eight valence electrons; H and He seek two.

How do molecules and compounds differ?

A molecule contains two or more bonded atoms. A compound contains two or more different kinds of bonded atoms. H2 is a molecule; H2O is both.

What are mixtures, solutions, solvents, and solutes?

A mixture contains physically combined, unbonded substances. A solution is homogeneous. The solvent is most abundant; solutes are dissolved in smaller amounts.

How can solution concentration be expressed?

Concentration may be expressed as percent solute, mg/dL, or molarity. Molarity is moles of solute per liter of solution.

What are the three main differences between mixtures and compounds?

Mixtures lack chemical bonds, can be physically separated, and may be homogeneous or heterogeneous. Compounds are bonded, require bond-breaking to separate, and are homogeneous.

What is a chemical bond?

A chemical bond is an energy relationship involving the electrons of reacting atoms. Electrons determine whether and which type of bond forms.

How do ionic bonds form, and what are cations and anions?

Ionic bonds form when electrons transfer and opposite ions attract. Cations lose electrons and become positive; anions gain electrons and become negative.

How do covalent bonds form, and what are single, double, and triple bonds?

Covalent bonds share valence electrons. Single bonds share 2 electrons, double bonds share 4, and triple bonds share 6.

How do nonpolar and polar covalent bonds differ?

Nonpolar bonds share electrons equally. Polar bonds share unequally, creating partial charges. The more electronegative atom becomes partially negative.

What are hydrogen bonds, and why are they important?

Hydrogen bonds are weak attractions between a partially positive hydrogen and an electronegative atom. They help give water surface tension and stabilize proteins and DNA.

What is the order of bond strength?

Covalent bonds are strongest, ionic bonds have intermediate strength, and hydrogen bonds are weakest.

What are chemical reactions, reactants, and products?

Chemical reactions form, rearrange, or break bonds. Reactants are starting substances and products are ending substances. Equations must be balanced.

How do subscripts and coefficients differ in chemical equations?

A subscript shows bonded atoms within one substance. A coefficient shows the number of separate atoms or molecules.

How do synthesis, decomposition, and exchange reactions differ?

Synthesis joins substances: A + B → AB. Decomposition separates them: AB → A + B. Exchange reactions both break and form bonds.

What are oxidation and reduction?

Oxidation is loss of electrons: OIL. Reduction is gain of electrons: RIG.

How do exergonic and endergonic reactions differ?

Exergonic reactions release energy and leave products with less potential energy. Endergonic reactions absorb energy and leave products with more potential energy.

What are reaction reversibility and chemical equilibrium?

Reversible reactions can proceed in either direction. At equilibrium, forward and reverse reactions occur at equal rates, so neither direction dominates.