Chap 2 Flashcards
Matter
Anything that takes up space and has mass.
Element
Any substance that cannot be broken down to any other substance by chemical reactions.
Compound
A substance consisting of two or more different elements combined in a fixed ratio. (NaCl is an example of 1:1 ratio and H20 is a 2:1 ratio)
Essential elements
A chemical element required for an organism to survive, grow, and reproduce.( These vary between organisms, humans need 25 plants need 17)
Trace elements
An element indispensable for life but required in extremely minute amounts.
Atom
The smallest unit of matter that retains the properties of an element.( C stands for both the element carbon and single a carbon atom)
Subatomic particles
Things like protons, neutrons and electrons.
Neutron
A subatomic particle having no electrical charge (electrically neutral), with a mass of about 1.7* 10-24 g. In the nucleus of the atom.
Proton
A subatomic particle with a single positive electrical charge. Found in the nucleus of an atom.
Electron
A subatomic particle with a single negative electrical charge and a mass 1/2000 that of a N or P. Electrons move around the nucleus of an atom.
Atomic nucleus
An atoms dense central core, containing protons and neutrons
Dalton
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 the nucleus of an atom, unique for each element and designated by a subscript. (Carbon has an atomic # of 6 so that means it has 6 protons. The # is also the amount of electrons an atom has, so carbon has 6 electrons.)
Mass number
The total of protons and neutrons in an atoms nucleus. (To find the how many neutrons an atom has ,you do mass # - atomic #. Carbons is 12-6 so carbon has 6 neutrons.)
Atomic mass
The total mass of an atom, numerically equivalent to the mass in grams of 1 mole of the atom. (For an element with more than one isotope, the atomic mass is the average mass of the naturally occurring isotopes, weighted by their abundance.)
