CH.2 Flashcards
Matter
—anything that has mass and
occupies space
3 states of matter
solid, liquid, gas
Energy
capacity to do work
kinetic
energy in action
potential
stored energy
chemical energy
stored in bonds of chemical substances
Electrical energy
– Results from movement of charged particles
Mechanical energy
Directly involved in moving matter
• Radiant or electromagnetic energy
Travels in waves (e.g., visible light, ultraviolet
light, and x-rays)
Elements
– Matter is composed of elements
– Elements cannot be broken into simpler
substances by ordinary chemical methods
– Each has unique properties
• Atoms
Unique building blocks for each element – Give each element its physical & chemical properties – Smallest particles of an element with properties of that element
Atomic symbol
One- or two-letter chemical shorthand for
each element
Four elements make up 96.1% of body mass
Element Carbon Hydrogen Oxygen Nitrogen
9 elements make up 3.9% of body mass
Element Calcium Phosphorus Potassium Sulfur Sodium Chlorine Magnesium Iodine Iron
11 elements make up < 0.01% of body mass
Element Chromium Copper Fluorine Manganese Silicon Zinc
Atoms
composed of subatomic particles – Protons, neutrons, electrons • Protons and neutrons found in nucleus • Electrons orbit nucleus in an electron cloud
Nucleus of atoms
Almost entire mass of the atom • Neutrons • Carry no charge • Mass = 1 atomic mass unit (amu) • Protons • Carry positive charge • Mass = 1 amu
Electrons in orbitals within electron cloud
• Electrons in orbitals within electron cloud
– Carry negative charge
– 1/2000 the mass of a proton (0 amu)
– Number of protons and electrons always
equal
Different elements contain different
numbers of subatomic particles
Hydrogen has 1 proton, 0 neutrons, and 1
electron
– Lithium has 3 protons, 4 neutrons, and 3
electrons
Atomic number
Number of protons in
nucleus
– Written as subscript to left of atomic symbol Ex. 3Li
Mass number
Total number of protons and neutrons in nucleus • Total mass of atom – Written as superscript to left of atomic symbol • Ex. 7Li
• Isotopes
– Structural variations of atoms
– Differ in the number of neutrons they contain
– Atomic numbers same; mass numbers
different
Atomic weight
Average of mass numbers (relative weights)
of all isotopes of an atom
Radioisotopes - Heavy isotopes decompose to more stable forms
Spontaneous decay called radioactivity
– Similar to tiny explosion
– Can transform to different element
Can be detected with scanners