Hole’s Human Anatomyand Physiology 12th Edition

Chapter 2, pp. 51-55Introduction to Chemistry, part I

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Chemical Basis of Life

Why study chemistry in anAnatomy and Physiology class?

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Matter

•takes up space + has weight• solids, liquids and gases

•atom = smallest stable unit of matter

• different types of atoms form from different elements

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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

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http://www.corrosionsource.com/handbook/periodic/periodic_table.gif

Atomic StructureAtoms - composed of subatomic particles:

• protons• + charge• mass = 1

• neutrons• no charge• mass = 1

• electrons• charge• almost 0 mass

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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

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COMPARISON OF SUB-ATOMIC PARTICLESLocation Charge Mass Can transfer from one

atom to another?

Proton

Neutron

Electrons

An _____ has # protons = # electrons.A) ion C) both A & B are correctB) 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

Atomic Weight # protons + # neutrons electrons do not contribute weight

Ex. oxygen has 8 protons and 8 neutrons Atomic weight = O16

Isotopes atoms have same number of protons but a

different number of neutrons same atomic number, different atomic weight

ex. oxygen forms isotopes (O16, O17, O18) same element!

How many protons in O16? O17? O18? How many neutrons?

unstable isotopes are radioactive and emit energy

– used in medicine and research

Atomic Number Determines the ElementAtomic 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?

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Electrons• found in electron shells (energy shells)• each shell holds a limited number of electrons

• 1st shell holds up to 2 electrons• 2nd shell holds up to 8 electrons• 3rd 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

H2 C6H12O6 H2O

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Concept Review1. 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?