Lec2notescomplete

Lec2notescomplete - Bio1A Dr. McCray Lec 2 Complete Notes...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Bio1A Dr. McCray Lec 2 Complete Notes 1 Chapter 2 The Chemical Context of Life Matter, elements and compounds ¢ Organisms are composed of matter ¢ Matter is anything that takes up space and has mass ¢ Matter is made up of elements ¢ An element is a substance that cannot be broken down to other substances by chemical reactions ¢ A compound is a substance consisting of two or more elements in a fixed ratio Fig. 2-2 Essential Elements of Life ¢ Carbon , hydrogen , oxygen , and nitrogen make up 96% of living matter ¢ Remaining 4% consists of calcium , phosphorus , potassium , and sulfur ¢ Trace elements - required in minute quantities Table 2.1, Fig. 2-3 Structure of atoms ¢ Element consists of unique atoms ¢ Atom is the smallest unit of matter that still retains the properties of an element ¢ Atoms are composed of subatomic particles: ¢ Neutrons (no electrical charge) ¢ Protons (positive charge) ¢ Electrons (negative charge) ¢ Neutrons and protons form the atomic nucleus ¢ Electrons form a cloud around the nucleus Fig. 2-4 Atomic Number and Atomic Mass ¢ Atomic number is the number of protons ¢ An element’s mass number is the sum of protons plus neutrons in the nucleus ¢ Atomic mass , the atom’s total mass, can be approximated by the mass number Isotopes ¢ Isotopes = 2 atoms w/ same # protons, different # of neutrons ¢ Most isotopes are stable, but some are radioactive , giving off particles and energy ¢ Some applications of radioactive isotopes in biological research: ¢ Dating fossils ¢ Tracing atoms through metabolic processes ¢ Diagnosing medical disorders Fig. 2-6
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Bio1A Dr. McCray Lec 2 Complete Notes 2 The Energy Levels of Electrons
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 4

Lec2notescomplete - Bio1A Dr. McCray Lec 2 Complete Notes...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online