Chapter 2 - The Chemical Context of Life Flashcards
Element
A substance that cannot be broken down to other substances by chemical reactions.
Compound
A substance consisting of two or more elements in a fixed ratio.
Trace elements
An element indispensable for life but required in extremely minute amounts.
Atom
The smallest unit of matter that still retains the properties of an element.
Neutrons
A subatomic particle with no electrical charge.
Protons
A subatomic particle with a positive electrical charge.
Electrons
A subatomic particle with a negative electrical charge. Form a cloud around the nucleus.
Atomic nucleus
Contains protons and neutrons. Almost the same mass and are measured in Daltons.
Daltons
A measure of mass for atoms and subatomic particles; the same as the atomic mass unit, or amu.
Atomic number
The number of protons in an atom, unique for each element and designated by a subscript to the left of the elemental symbol.
Atomic mass
The total mass of an atom, which is the mass in grams of 1 mole of the atom.
Mass number
The sum of the number of protons and neutrons in an atoms nucleus.
Isotope
One of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass.
Radioactive Isotope
An isotope that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy.
Some applications of radioactive isotopes in biological research are
- Dating fossils
- Tracing atoms through metabolic processes
- Diagnosing medical disorders
Potential energy
The energy that matter has because of its location or structure
Electron shell
An electron’s state of potential energy. Also called energy level.
The chemical behavior of an atom is determined by…
valence electrons.
Valence electrons
Electrons in the outermost electron shell, or valence shell.