Lecture 2: Basics of Chemistry

Atom

The smallest chemical unit that makes up all matter.

Periodic Table

A table that lists and organizes all known elements.

Elements of Life

The four elements that make up most living things.

Atomic Number

The number of protons in each atom of an element, determining the element's identity.

Mass Number

The total number of protons and neutrons in an atomic nucleus.

Isotope

Different forms of the same element that have varying numbers of neutrons.

Atomic Weight

The average mass of an element on Earth, considering the abundance of different isotopes.

Radioisotope

An isotope with an unstable atomic nucleus that releases radiation during decay.

Ion

An atom with a net electric charge due to the loss or gain of electrons.

Chemical Bond

A lasting attraction between atoms to form molecules.

Covalent Bond

A bond formed when atoms share electrons.

Ionic Bond

A chemical bond formed between atoms with opposite charges due to electron transfer.

Polar Covalent Bond

A bond formed between atoms of different electronegativity resulting in unequal sharing of electrons.

Hydrogen Bond

A weak bond formed between the slight positive charge of hydrogen in one molecule and the slight negative charge in another molecule.

Cohesion

The tendency of water molecules to stick to one another.

Adhesion

The property of water to form hydrogen bonds with other molecules.

Specific Heat

The amount of heat needed to change the temperature of a substance.

Heat of Vaporization

The heat a liquid must absorb for a liquid to be converted to gas.

Hydrophobic Force

The force that brings two nonpolar surfaces together by excluding water between them.

Solvent

The greater liquid in a solution that dissolves other substances.

Amphipathic

Molecules that have both hydrophilic and hydrophobic regions.

pH

A measure of the concentration of hydrogen ions (H+) in a solution.

Acidic Solution

A solution with a high concentration of hydrogen ions (H+), pH below 7.

Basic Solution

A solution with a low concentration of hydrogen ions (H+), pH above 7.

Living things are mostly composed of what 4 elements

carbon, nitrogen, hydrogen, and oxygen

Applications of radioactive isotopes

dating fossils, tracing atoms through metabolic processes, diagnosing medical disorders

what is it called when some atoms attract electrons strongly

highly electronegative

what is it called when atoms only attract electrons weakly

not very electronegative

water adhesion and cohesion allow water molecules to ___ from a trees roots to its leaves

climb

evaporative cooling

as a liquid evaporates, its remaining surface cools

dehydration synthesis

reactions that build molecules

hydrolysis

process that breaks down molecules