Chapter 2 Biology: Basic Chemistry - Chemical Elements 2.1

Flashcards covering the fundamentals of matter, atomic structure, and chemical elements as presented in Chapter 2 of the Biology lecture.

Matter

Anything that takes up space and has mass; it is composed in four distinct states: solid, liquid, gas, or plasma.

Elements

Basic substances that cannot be broken down into simpler substances and make up all nonliving and living matter.

CHNOPS

The six elements basic to life that make up $95\%$ of the body weight of organisms: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.

John Dalton

The English scientist who developed the atomic theory.

Atom

The smallest part of an element that displays the properties of that element.

Atomic symbol

The shared name for an element and its atom, such as $H$ for hydrogen and $Na$ for sodium.

Protons

Positively charged $(+)$ particles located within the nucleus of an atom.

Neutrons

Uncharged particles located within the nucleus of an atom.

Electrons

Negatively charged $(-)$ particles located in the area outside the nucleus of an atom.

Atomic number

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

Mass number

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

Isotopes

Atoms of the same element having the same atomic number but a different mass number due to a variation in the number of neutrons.

Atomic mass

The average mass for all the isotopes of an atom, which is equal to the mass number.

Radioactive isotopes

Isotopes that are unstable and must break down over time to become stable.

Radioactive decay

The process by which an unstable isotope breaks down to achieve stability.

Bohr model

A representation of electron shells around the nucleus that shows the average energy levels of an electron.

Valence shell

The outermost shell of an atom, which determines many of its chemical properties.

Octet rule

The principle stating that an outer shell is most stable when it contains $8$ electrons, or $2$ electrons if the atom has only one shell.