Textbook Notes (280,000)
US (110,000)
UM (1,000)
BIL (200)
BIL 150 (90)
Chapter 2

BIL 150 Chapter Notes - Chapter 2: Atomic Nucleus, Atomic Number, Covalent Bond

Course Code
BIL 150
Gaines Michael

This preview shows page 1. to view the full 4 pages of the document.
Chapter 2 – The Chemical Context of Life
Organisms are composed of matter, which is anything that takes up
space and has mass
Elements and compounds
oElement – a substance that cannot be broken down to other
substances by chemical reactions (Na)
oCompound – a substance consisting of two or more different
elements combined in a fixed ratio (H2O)
The Elements of Life
oOf the 92 natural elements, about 20-25% are essential elements,
meaning that an organism needs them to live a healthy life and
reproduce (humans need 25 elements, plants need 17)
o96% of living matter is made up of oxygen, carbon, hydrogen, and
oTrace elements are required by an organism in only minute
Fe (iron) is needed by all forms of life
Atom – the smallest unit of matter that still retains the properties of an
oSubatomic particles – neutrons, protons, electrons
oProtons and neutrons are packed together tightly in the atomic
oProtons and neutrons have masses close to 1 Dalton
Atomic number (# of protons) and mass number (protons + neutrons)
oIsotopes – some atoms that have more neutrons than other atoms
of the same element and therefore have greater mass
Radioactive isotope – one in which the nucleus decays
spontaneously, giving off particles and energy
The Energy Levels of Electrons
oEnergy – the capacity to cause change (by doing work)
You're Reading a Preview

Unlock to view full version