Principles of Life: Chemistry of Life

Vocabulary flashcards covering matter, atoms, bonds, water properties, acids/bases, pH, and organic chemistry.

CHNOPS

Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.

Matter

Anything that takes up space and has mass.

Element

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

There are 92 natural elements.

The naturally occurring elements in nature total 92.

Oxygen in the human body

Oxygen accounts for about 65% of body weight.

Carbon in the human body

Carbon accounts for about 18.5% of body weight.

Hydrogen in the human body

Hydrogen accounts for about 9.56% of body weight.

Nitrogen in the human body

Nitrogen accounts for about 3.3% of body weight.

Calcium in the human body

Calcium accounts for about 1.5% of body weight.

Phosphorus in the human body

Phosphorus accounts for about 1.0% of body weight.

Potassium in the human body

Potassium accounts for about 0.4% of body weight.

Sulfur in the human body

Sulfur accounts for about 0.3% of body weight.

Sodium in the human body

Sodium accounts for about 0.2% of body weight.

Chlorine in the human body

Chlorine accounts for about 0.2% of body weight.

Magnesium in the human body

Magnesium accounts for about 0.1% of body weight.

Trace elements

Elements present in the body at less than 0.01% by weight (e.g., B, Cr, Co, Cu, F, I, Fe, Mn, Mo, Se, Si, Sn, V, Zn).

Atom

The basic unit of matter, composed of protons, neutrons in the nucleus, and electrons moving around the nucleus.

Nucleus

The central region of an atom containing protons and neutrons.

Proton

Positively charged particle in the nucleus; number defines the element (atomic number).

Neutron

Electrically neutral particle in the nucleus; number can vary to form isotopes.

Electron

Negatively charged particle orbiting the nucleus; electrons can change, especially valence electrons.

Valence electrons

Electrons in the outermost shell involved in bonding.

Atomic number

The number of protons in the nucleus; defines the identity of the element.

Atomic weight

The weighted average mass of an element's isotopes.

Periodic table groups

Elements in the same vertical column have the same number of electrons in their outermost shell.

Molecule

Two or more atoms bonded together.

Compound

A substance consisting of two or more elements chemically bonded together.

Covalent bond

Bond formed by sharing electrons; can be single, double, or triple; generally strong.

Hydrogen molecule (H2)

Two hydrogen atoms bonded together by a covalent bond.

Single bond

A covalent bond formed by sharing one pair of electrons.

Double bond

A covalent bond formed by sharing two pairs of electrons.

Triple bond

A covalent bond formed by sharing three pairs of electrons.

Methane (CH4)

A carbon atom bonded to four hydrogens by single covalent bonds.

Ethane (C2H6)

Two carbons single-bonded to each other with surrounding hydrogens.

Ethylene (C2H4)

Two carbons with a double bond; unsaturated hydrocarbon.

Acetylene (C2H2)

Two carbons with a triple bond; unsaturated hydrocarbon.

Benzene

A ring C6H6 with alternating double bonds; aromatic hydrocarbon.

Polar covalent bond

Unequal sharing of electrons due to electronegativity differences; creates partial charges.

Electronegativity

The ability of an atom to attract electrons in a bond.

Ionic bond

Bond formed by transfer of electrons, producing oppositely charged ions that attract; weaker than covalent.

Cation vs Anion

Cation: positively charged ion (e.g., Na+); Anion: negatively charged ion (e.g., Cl-).

Salt

Ionic compound composed of cations and anions; commonly dissolves in water.

Hydrogen bonds

Weak bonds between polar molecules due to partial charges; important in DNA and water.

Van der Waals forces

Weak attractions between molecules or within molecules due to transient dipoles; help shape molecules.

Solvent

Substance that dissolves solutes; water is the universal solvent.

Hydrophilic vs Hydrophobic

Hydrophilic: substances that attract water; Hydrophobic: substances that repel water.

pH

A measure of H+ concentration in a solution; scale from 0 (acidic) to 14 (basic), 7 is neutral.

Acid

Substance that releases H+ in water; pH below 7 (e.g., HCl).

Base

Substance that releases OH- in water; pH above 7 (e.g., NaOH).

Buffer

Substance or system that resists changes in pH by absorbing or releasing H+ or OH-.

Water and life

Water’s properties (high heat capacity, high heat of vaporization, cohesion, adhesion, surface tension) support life.

Ice density

Frozen water is less dense than liquid water and expands when it freezes.

Organic chemistry

Chemistry of the living world; molecules that contain carbon and hydrogen.

Organic molecule

A molecule that contains carbon and hydrogen.