Chapter 2 Flashcards
Anything that occupies space and has mass
Matter
A pure substance that cannot be broken down into simpler substances by ordinary chemical of physical techniques
Element
The smallest unit that retains the chemical and physical properties of an element
Atoms
An element that occurs in organisms in very small quantities. In nutrition a mineral el required by organisms only in small amounts
Trace elements
The name of a molecule written in chemical shorthand
Formula
A unit of atoms combined chemically in fixed numbers and ratios
Molecules
The part of an atom which consists of subatomic particles called protons and neutrons
Atomic nucleus
A molecule whose component atoms are different
Compounds
Uncharged subatomic particle in the nucleus of an atom
Neutrons
A subatomic particle in the nucleus of an atom that carries one unit of charge
Protons
Negatively charged particles outside the nucleus of an atom
Electrons
The number of protons in the nucleus of each kind of atom
Atomic number
A distinct form of the atoms of an element, all with the same number of protons but different number of neutrons
Isotopes
The total number of protons and neutrons in the atomic nucleus
Mass number
The amount of matter in an object
Mass
A standard unit of mass, around 1.66 x 10 - 23 grams
Dalton
The giving off of particles of matter and energy by decaying nuclei
Radioactivity
A measure of the pull of gravity of an object
Weight
An unstable, radioactive isotope
Radioisotope
A dating technique that uses clockwork decay of unstable isotopes to estimate the age of organic material, rocks, or fossils that contain them
Radiometric dating
The region of space where the electron lives most of the time
Orbital
Isotope used to label molecules so that they can be tracked as they pass through biochemical reactions
Tracers
Regions of space within an atom where electrons are found. Also referred to as shells
Energy levels
Regions of space within an atom where electrons are found. Also referred to as energy levels
Shells
Link formed when atoms of reactive elements combine into molecules
Chemical bonds
An electron in the outermost energy level of an atom
Valence electrons
A bond that results from electrical attractions between atoms that gain or lose valence electrons completely
Ionic bonds
A positively charged ion
Cation