Biochemistry Concepts Quiz

Atomic Structure

• Matter is a substance with mass and occupies space.
• Matter exists in solid, liquid, and gas forms.
• All matter is composed of atoms.
• An atom is the smallest particle with the chemical properties of an element.
• There are 92 naturally occurring elements.
• Elements are organized in the periodic table.
• Elements are categorized as major, minor, or trace elements based on their percentage in the human body.
• Major elements comprise ~99% of the human body.
• Atoms are comprised of protons, neutrons, and electrons.
• Protons have a positive charge and a mass of 1 amu.
• Neutrons have no charge and a mass of 1 amu.
• Electrons have a negative charge and are ~1/800th the mass of a proton or neutron.
• Protons and neutrons are located in the atomic nucleus.
• Electrons are found in orbitals or electron shells.
• Each shell has a limited number of electrons it can hold.
• The outermost shell is called the valence shell.
• Isotopes are atoms of the same element with the same number of protons and electrons but different numbers of neutrons.

Isotopes

• Isotopes have essentially identical chemical characteristics.
• Carbon exists in three isotopes: carbon-12, carbon-13, and carbon-14.
• Some isotopes are radioactive (radioisotopes).

Ions and Ionic Compounds

• Ions are atoms or groups of atoms with a positive or negative charge.
• Ions are formed when atoms lose or gain electrons.
• Cations are positively charged ions formed by losing electrons.
• Anions are negatively charged ions formed by gaining electrons.
• Polyatomic ions are ions formed by more than one atom.
• Ionic bonds form through electrostatic interactions between cations and anions.
• Ions function as electrolytes, enabling electrical current in solutions.

Covalent Bonding

• Covalent bonds form when atoms share electrons.
• Molecules are formed when atoms covalently bond.
• Molecular compounds are composed of two or more different elements.
• Covalent bonds can be single, double, or triple.
• Polar covalent bonds occur when electrons are unequally shared.
• Nonpolar covalent bonds occur when electrons are equally shared.
• Electronegativity influences the sharing of electrons.

Polar and Nonpolar Molecules

• Nonpolar molecules form predominantly with the same or same similar elements.
• Polar molecules form from bonding between different elements.
• Intermolecular attractions involve weak chemical attractions between molecules.
• Hydrogen bonds occur between a partially positive hydrogen atom and a partially negative atom (oxygen or nitrogen).

Water Properties

• Water is a polar molecule.
• Water molecules form hydrogen bonds with each other.
• Water's properties include cohesion, adhesion, surface tension, high heat capacity, and high heat of vaporization.
• Water is called the universal solvent.
• Water dissolves polar and charged substances (hydrophilic).

Mixtures

• Water mixtures include suspensions, colloids, and solutions.
• Suspensions have larger particles than 100 nm and settle.
• Colloids have particles between 1 and 100 nanometers and do not settle.
• Solutions have particles smaller than 1 nm and do not settle.

Acidic and Basic Solutions

• Water can dissociate to form hydronium (H3O+) and hydroxide (OH−) ions.
• Acids donate H+, increasing H+ concentration.
• Bases accept H+, decreasing H+ concentration.
• pH measures the concentration of H+ ions.
• Buffers maintain a relatively constant pH.