Hole’s Human Anatomy and Physiology 12 th Edition Chapter 2, pp Introduction to Chemistry, part I Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1-1

Chemical Basis of Life Why study chemistry in an Anatomy and Physiology class? 2-2

Matter takes up space + has weight solids, liquids and gases atom = smallest stable unit of matter different types of atoms form from different elements 2-3

Elements 92 naturally occurring elements additional created by man form all matter, both living and non-living 26 elements found in humans each type of element is composed of chemically identical atoms an atom is the smallest particle of an element 2-3

Atomic Structure Atoms - composed of subatomic particles: protons + charge mass = 1 neutrons no charge mass = 1 electrons charge almost 0 mass 2-4

Atomic Structure Nucleus dense center of atom protons and neutrons Orbiting the Nucleus electron cloud can remove or add electrons to create ions ion = charged atom atom = electrically neutral 2-4

COMPARISON OF SUB-ATOMIC PARTICLES LocationChargeMassCan transfer from one atom to another? Proton Neutron Electrons An _____ has # protons = # electrons. A) ionC) both A & B are correct B) atom D) neither A nor B are correct If an atom loses or gains an electron, is it electrically neutral? What is it then named?

Atomic Weight  # protons + # neutrons  electrons do not contribute weight Ex. oxygen has 8 protons and 8 neutrons  Atomic weight = O 16

Isotopes atoms have same number of protons but a different number of neutrons  same atomic number, different atomic weight ex. oxygen forms isotopes (O 16, O 17, O 18 ) same element! How many protons in O 16 ? O 17 ? O 18 ? How many neutrons? unstable isotopes are radioactive and emit energy – used in medicine and research

Atomic Number Determines the Element Atomic Number # protons each element has a unique atomic number will the number of protons in an atom also determine how many electrons there are in an atom? f an atom has 9 protons, how many electrons will it have? 2-5

Electrons found in electron shells (energy shells) each shell holds a limited number of electrons 1 st shell holds up to 2 electrons 2 nd shell holds up to 8 electrons 3 rd shell holds up to 8 electrons lower shells are filled first outermost shell is known as the “valence” shell a full valence shell  stable atom (unreactive) unstable atoms will react with each other to form stable compounds or molecules Will an unstable atom have a full valence shell? 2-8 “Octet rule”

Fill in the blanks for H, C and Na ____ _____ ____ ____ ____

Molecules and Compounds Molecule –when two or more atoms chemically combine Compound – when two or more atoms of different elements chemically combine in defined proportions. Molecular formulas – elements present and the number of each atom present in the molecule H 2 C 6 H 12 O 6 H 2 O 2-7

Concept Review 1. Which particle of the atom: 2 - can transfer from one atom to another? - creates isotopes? - has almost no mass? - gives the atom its properties? 2. Which of the following are “stable” atoms? 3. What do you think will happen to each of the non- stable atoms below?