Chapter 2 – Basic Chemistry (Video Notes)

A comprehensive set of practice flashcards covering key concepts from the lecture notes on basic chemistry, atoms, bonds, reactions, acids/bases, and biomolecules.

What is Chemistry concerned with?

Matter and Energy

What is matter?

Anything that has mass and occupies space, existing in solid, liquid, or gas states

What are the three states of matter?

Solid, liquid, and gas

What is energy?

The capacity to do work or put matter into motion

What are the two possible states of energy?

Kinetic energy (energy in motion) and Potential energy (energy due to location or structure)

Give examples of potential energy.

Water held back by a dam, chemical energy in gunpowder, gasoline, or glucose

What are the four forms of energy listed?

Chemical energy, Electrical energy, Mechanical energy, Radiant (electromagnetic) energy

What happens to some energy when energy is converted?

Some energy is lost as heat

What are atoms and elements?

Atoms are the basic building blocks of matter; elements are categories based on their structure; all atoms of an element have the same properties

How many subatomic particles are in atoms and what are they?

Protons (p+), Neutrons (n0), and Electrons (e−)

Where are protons and neutrons found and what is their mass?

In the nucleus; mass ~1 atomic mass unit (amu) for both

Where do electrons reside and what is their mass?

Electrons orbit the nucleus in shells; mass ~0 amu (essentially negligible)

In an atom, how do the numbers of protons and electrons relate?

The number of protons equals the number of electrons (p+ = e−) so the net charge is neutral

What are the two models of atomic structure?

Planetary model and orbital (electron cloud) model

What determines the identity of an element?

The number of protons (atomic number)

Give an example of how isotopes differ.

Isotopes of an element have the same number of protons but different numbers of neutrons (different mass numbers)

What is an atomic symbol?

One- or two-letter chemical shorthand for an element; first letter capitalized, second if present is lower-case

From where does the symbol Na originate?

Sodium; from the Latin natrium

What is atomic number and where is it found?

Number of protons; determines identity; usually shown as a subscript to the left of the symbol (often not written)

What is mass number?

Total number of protons and neutrons in the nucleus; mass of the atom; shown as a superscript to the left of the symbol

What are isotopes?

Structural variations of the same element with the same atomic number but different mass numbers

What is atomic weight?

Average of the mass numbers of all isotope forms based on their natural abundance

What are radioisotopes?

Heavy, unstable isotopes that decay and are detectable in medical imaging

What does the periodic table show about an element’s numbers?

Atomic number (p+) in the upper left, atomic weight underneath the symbol; mass number is not shown on the table

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

Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N)

What are the 9 elements making up 3.9% of the body?

Ca, P, K, S, Na, Cl, Mg, I, Fe (symbols to be recognized)

What are trace elements?

Elements that make up less than 0.01% of the body

What is a molecule?

Two or more atoms bonded together

What is a compound?

A molecule with two or more different kinds of atoms bonded together

Give two examples of molecules and compounds.

Examples: C6H12O6 and H2O

What is a solution, colloid, and suspension?

Three basic types of mixtures: Solutions (homogeneous), Colloids, Suspensions

How do solute particles behave in a solution?

Solute particles are very tiny and do not settle out or scatter light

How do colloids differ from solutions?

Solute particles are larger than in a solution, they scatter light, and do not settle out

What characterizes a suspension?

Solute particles are very large, settle out, and may scatter light

What are the properties of solutions in terms of composition?

Solutions are homogeneous mixtures with solvent and solute; concentration can be described as percent solution, mg/dL, or molarity

What is the difference between mixtures and compounds regarding separation?

Mixtures can be separated by physical means (e.g., straining); compounds are bonded chemically and not easily separated by physical means

What is an atomic symbol and how is it written for ions?

Symbols like Na, Cl or ions written as Na+, Cl−, Ca++

What does a molecular formula show?

Types and amounts (subscripts) of atoms bonded in a molecule; leading numbers indicate how many molecules

What holds atoms together in chemical bonds?

Outer-shell electrons (valence electrons) forming chemical bonds

What is the valence shell?

The outer electron shell involved in bonding

How many electrons can the first three shells hold according to the notes?

Shell 1 holds 2, Shell 2 holds 8, Shell 3 holds 8

Which electrons participate in bonding?

Valence electrons

What makes elements reactive or stable?

Reactivity is determined by whether the valence shell is full or not; full valence shells are stable and nonreactive

What are the three major types of chemical bonds?

Ionic bonds, Covalent bonds, Hydrogen bonds

How is an ionic bond formed?

Transference of electrons resulting in ions that attract due to opposite charges

What are ions?

Atoms that have gained or lost electrons and become charged (anions negative, cations positive)

What happens in a typical Na and Cl example?

Sodium loses an electron to become Na+, chlorine gains an electron to become Cl−; they attract to form NaCl

What are salts?

Ionic compounds that form crystals when many ions aggregate (e.g., NaCl)

What is a covalent bond?

Bond formed by sharing one or more pairs of valence shell electrons

What are single, double, and triple covalent bonds?

Single shares one pair; double shares two pairs; triple shares three pairs

What is a polar covalent bond?

Unequal sharing of electrons leading to partial charges; example: water

What is a nonpolar covalent bond?

Equal sharing of electrons; examples include CO2

What is a hydrogen bond?

Weak attraction between a slightly positive hydrogen and a slightly negative atom on another molecule

Why can water support surface phenomena like a water strider?

Hydrogen bonds create high surface tension

What is a chemical reaction?

Process where bonds form, rearrange, or break to transform reactants into products; reactions must be balanced

Give an example of a balanced chemical equation.

2H2 + O2 = 2H2O

What are the three main types of chemical reactions?

Synthesis, Decomposition, Exchange (displacement) reactions

What happens in a synthesis reaction?

Two or more substances combine to form a larger, more complex molecule

What happens in a decomposition reaction?

A larger molecule breaks down into smaller, simpler products

What happens in an exchange (displacement) reaction?

Bonds are broken and formed; ions and molecules exchange partners; e.g., ATP transfers phosphate to glucose

What is a redox reaction?

Reactions involving transfer of electrons; oxidation is loss, reduction is gain of electrons

Which molecule example illustrates a redox process involving oxygen as an electron acceptor?

General redox example: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP (oxidation of glucose, reduction of O2)

What is energy flow in chemical reactions?

Reactions can be exergonic (release energy) or endergonic (absorb energy)

Are chemical reactions reversible?

Theoretically yes; most reactions are reversible (A + B → AB and AB → A + B)

What factors affect the rate of chemical reactions?

Temperature, concentration of reactants, particle size, catalysts (including enzymes)

What is a catalyst?

A substance that increases the rate of a reaction without being consumed; enzymes are biological catalysts

What is biochemistry?

The study of chemical composition and reactions of living matter

What are inorganic compounds?

Compounds that do not contain carbon; water is the most abundant inorganic compound in life

What are salts and electrolytes?

Salts are ionic compounds that dissociate into ions in water; common electrolytes include Na+, Cl−, K+, Ca++

What is an acid?

Ionic compounds that release H+ ions in solution

What is a base?

Ionic compounds that accept or remove H+ ions in solution (often contain OH−)

What is pH?

A measure of the concentration of free H+ ions in a solution; 0 is most acidic, 14 most basic, 7 neutral

Is the pH scale linear or logarithmic?

Logarithmic; each whole-number change represents a tenfold change in H+ concentration

What does neutralization mean in acids and bases?

An acid reacts with a base to form water and a salt

What are buffers?

Substances that resist pH changes by absorbing or releasing H+ as needed

Why are buffers important to living systems?

Cells are very sensitive to pH changes; buffers help maintain stable pH

What makes organic compounds different from inorganic compounds?

Organic compounds contain carbon and are typically large and complex molecules

What are the major categories of organic macromolecules?

Carbohydrates, Lipids, Proteins, Nucleic Acids

What are dehydration synthesis and hydrolysis?

Dehydration synthesis links monomers by removing water; hydrolysis breaks bonds by adding water

What is a polymer?

Many monomers joined together to form a large molecule; 2 = dimer, 3 = trimer, 4 = tetramer, many = polymer

What constitutes carbohydrates?

Contain C, H, O in a 2:1 hydrogen to oxygen ratio; monosaccharides, disaccharides, polysaccharides

Name common monosaccharides mentioned.

Glucose, Fructose, Galactose

What are disaccharides?

Two linked monosaccharides; examples include sucrose, maltose, lactose

What is a polysaccharide?

A long polymer of monosaccharides; example: glycogen

What are lipids and their main types?

Compounds with C, H, O (sometimes P); insoluble in water; main types: triglycerides, phospholipids, steroids

What is a triglyceride?

Three fatty acids bonded to a glycerol molecule; fats and oils

What is a phospholipid and its significance?

Modified triglyceride with two fatty acids and a phosphorus-containing group; amphipathic; main component of cell membranes

What is the phospholipid bilayer?

Two layers with polar heads facing water and nonpolar tails inward; forms cell membranes

What are steroids and why are they important?

Lipids with four interlocking hydrocarbon rings; cholesterol is the best-known steroid and a precursor to vitamin D, steroid hormones, and bile salts

What are essential roles of cholesterol?

Structural basis for steroids and important for cell membranes

What are proteins and their general functions?

Proteins comprise 20–30% of cell mass; functions include structure and as catalysts (enzymes)

What are amino acids and how many exist?

20 different amino acids; each has a common core and a variable R group

What bonds link amino acids?

Peptide bonds formed by dehydration synthesis; hydrolysis breaks peptide bonds with water

What are the four levels of protein structure?

Primary structure; Secondary structure (alpha helices and beta pleated sheets); Tertiary structure; Quaternary structure

What determines a protein’s secondary structure?

Hydrogen bonds in the peptide backbone create alpha helices and beta sheets

What is the tertiary structure of a protein?

3D folding of the polypeptide driven by hydrogen bonds, hydrophobic interactions, and covalent bonds

What is the quaternary structure?

Two or more polypeptide chains (subunits) combined to form a functional protein

What are enzymes?

Globular proteins that act as biological catalysts; highly specific for particular substrates

How are enzymes named and categorized?

Often end in -ase; the name often describes the reaction catalyzed (e.g., hydrolase, oxidase)

How do enzymes lower activation energy?

They provide a pathway with lower energy barrier, speeding up the reaction