Chapter 1-5 Biology Lecture Notes: Study of Life & Chemical Foundations

Vocabulary flashcards covering topics from Chapter 1 through 5, including scientific method principles, chemical foundations, bonding types, properties of water, early life hypotheses, carbon isomers, and biological macromolecules.

Atom

The smallest unit of matter that retains all chemical properties of an element.

Element

A type of matter consisting of only one kind of atom that cannot be broken down into simpler substances.

CHNOPS

An acronym for the six elements that make up $98\%$ of all living matter: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.

Trace elements

Elements required by an organism in only small or minute quantities.

Atomic number

The total number of protons in the nucleus of an atom.

Mass number

The sum of the number of protons and neutrons in the nucleus of an atom.

Valence electrons

Electrons residing in the outermost electron shell of an atom.

Octet rule

The principle that atoms are most stable when their outermost valence shell contains $8$ electrons.

Molecule

A structure formed when two or more atoms are chemically bonded together.

Compound

A substance consisting of atoms combined from two or more different elements.

Ionic bond

An attraction between oppositely charged ions (anions and cations).

Cation

A positively charged ion formed when an atom loses one or more electrons.

Anion

A negatively charged ion formed when an atom gains one or more electrons.

Covalent bond

A strong chemical bond formed when atoms share pairs of electrons.

Electronegativity

An atom's measure of attraction for the electrons in a covalent bond.

Non-polar covalent bond

a covalent bond between 2 atoms that have similar electronegativities

Polar covalent bond

a covalent bond between 2 atoms whose electronegativities are very far apart from each other

Hydrogen bond

An electrostatic attraction formed when a hydrogen atom covalently bonded to an electronegative atom is attracted to another electronegative atom.

Van der Waals interactions

Transient electrostatic attractions between closely situated molecules due to non-evenly distributed electron charges.

Hydrophilic

Refers to polar substances that readily interact with or dissolve in water.

Hydrophobic

Refers to nonpolar molecules that do not interact well with or dissolve in water.

Cohesion

The attraction between water molecules bonding to other water molecules, which creates surface tension.

Adhesion

The attraction that causes water molecules to bond to other non-water molecules.

Acid

A substance that donates hydrogen ions ($H^+$) in an aqueous solution.

Base

A substance that donates hydroxide ions ($OH^-$) or accepts hydrogen ions ($H^+$) in an aqueous solution.

Buffer

A substance that minimizes changes in $H^+$ and $OH^-$ concentrations in a solution, maintaining pH stability.

Abiogenesis hypothesis

The hypothesis that life arose naturally on Earth from non-living organic molecules and chemical compounds.

Primordial soup theory

The theory that early surface bodies of water became rich in organic substances, providing conditions favorable for life to emerge via energy sources like lightning.

Isomers

Compounds that share the same molecular formula but possess different structures and properties.

Structural isomers

Isomers that differ in the covalent arrangement of their atoms.

Stereoisomers

isomers that share the same composition but vary in the spatial arrangement of their atoms

Enantiomers

Molecules that share the same chemical structure and bonds but differ in the 3D spatial placement of atoms, existing as non-superimposable mirror images.

Polymer

A long molecule built from many similar or identical repeating subunits linked by covalent bonds.

Monomer

A repeating chemical subunit that serves as a building block for polymers.

Methyl

CH3, nonpolar

Hydroxyl

OH, polar

Sulfhydryl

SH, polar

Aldehyde

COH, polar

Carbonyl/keto

=O, polar

Carboxyl

COOH, charged; acidic

Amino

NH2, charged; basic

Phosphate

PO4, charged; acidic

Order of electronegativity

O>N>C>H

Order for filling electron orbitals

1s —>2s—>2p—>3s—>3p