Chapter 2 Flashcards
Element
- 1 atom
- cannot be broken down further
Compound
- 2 or more elements in fixed ratio
- emergent properties, characteristics different form other elements
Elements Essential for Life
CHON(PS)
- Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur
(CHON) is 96% of elements required
Trace Elements
required in minute quantities
Atom
smallest unit of matter that still retains properties of an element
Neutron
- no charge, has mass
Protons
-positive charge
Electrons
negative charge
Atomic Number is equal to the number of
protons
Mass number is made up of
protons + neutrons
Atomic mass
total approximated mass
- in diagram number on bottom left
Isotopes
2 atomic forms of an element that have different numbers of neutrons
Radioactive Isotopes
decay spontaneously and give off particles and energy
Octet Rule
an atoms valence shell if full when it has 8 electrons, except for the innermost shell which is full with 2 electrons
First shell has the …. energy and the third shell has the …. energy
- lowest
- highest
A full shell means it is
not reactive and is stable
Carbon can bond in … places to fill shell
four
Covalent Bond
chemical bond formed by sharing electron pairs between two atoms
Nonpolar Covalent Bond
- electrons shared equally between two atoms
Polar Covalent Bond
- electrons are not shared equally between two atoms
Ionic Bond
attraction between an anion and a cation
Hydrogen Bond
attraction between two atoms already participating in other chemical bonds
- hold 2 or more water molecules together
All chemical reactions are
reversible
Chemical Equilibrium
reached when the forward and reverse reaction rates are equal
Four Emergent Properties of Water
- cohesive behavior
- expansion upon freezing
- ability to moderate temperature
- versatility as solvent
Adhesion
clinging of one substance to another
Surface Tension
how hard it is to break surface of a liquid, related to cohesion
Buffers
prevent from becoming too acidic or too basic
