Chapter 2 Biochemistry of Life

Matter

Anything that takes up space

Element

Substance that can’t be broken down by chemical means into other substances

90% of life consists of

Carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur

Atom

Smallest piece of an element that retains the characteristics of the element

The 3 subatomic particles

Protons, neutrons, electrons

Protons

Positive charge, mass of 1, found in the core

Electrons

Negative charge, no mass, floats around the core

Neutron

No charge, 1 mass, found in core

Atomic number

Number of protons

Charge

P-e

Atomic weight

P+n

Isotope

Atom with different neutrons, affects the weight

Chemicals bonds do what

Link atoms together

Atoms form

Molecules

Valence shell

Outermost shell of an atom

Ion

Charged atom

Cation

Positively charged atom

Full valence shell

Stable, won’t bond

Not full valence shell

Unstable, reactive

Period

Rows, number of electron orbits

Group

Columns, number of valence electrons

the 3 chemical bonds

Nonpolar covalent, polar covalent, ionic

Covalent bond

Each atoms unpaired electrons are shared by both nuclei

Non polar covalent bond

Electrons are evenly shared between 2 atoms, the bond is symmetrical

Polar covalent bond

Electrons are asymmetrically shared

Ionic bond

Electrons are transferred from 1 atom to another

Electronegativity

Measure of an atoms ability to attract electrons, helps determine the type of bond

Period table arranged atoms by electronegativity

Low to high

Elements with similar electronegativities will form

Nonpolar covalent bonds, right

2 elements with moderately different electronegativities will form

Polar covalent bonds, middle

Elements with very different electronegativities will form

Ionic bonds, left