Chapter 2 Chemistry comes alive

CHAPTER 2 CHEMISTRY COMES

ALIVESection 2a

Levels• Chemical• Cells• Tissue• Organ• Organ

system• Organism

Today we are working on…

Matter• The “stuff” of the universe• Anything that has mass and takes up

space• States of matter–Solid – has definite shape and volume–Liquid – has definite volume, changeable shape–Gas – has changeable shape and volume

Energy• The capacity to do work (put

matter into motion)• Types of energy–Kinetic – energy in action–Potential – energy of position; stored (inactive) energy

Forms of Energy• Chemical – stored in the bonds of

chemical substances • Electrical – results from the

movement of charged particles• Mechanical – directly involved in

moving matter• Radiant or electromagnetic –

energy traveling in waves (i.e., visible light, ultraviolet light, and X rays)

Energy Form Conversions• Energy is easily converted from one

form to another

• During conversion, some energy is “lost” as heat

• Energy is never created or destroyed

Composition of Matter• Elements are the fundamental

units of matter

• Elements – unique substances that cannot be broken down by ordinary chemical means

Properties of Elements• Each element has unique

physical and chemical properties–Physical properties – those detected with our senses–Chemical properties – pertain to the way atoms interact with one another

Major Elements of the Human Body• There are about 120 known elements

– 92 occur in nature – the rest are man-made• 96% of the body is made from four

elements - Know these –

• Oxygen (O)• Carbon (C)• Hydrogen (H)• Nitrogen (N)

Lesser Elements of the Human Body

• Lesser elements make up 3.9% of the body and include:–Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe)

Trace Elements of the Human Body

• Trace elements make up less than 0.01% of the body–They are required in minute amounts, and are found as part of enzymes

Composition of Matter• Each Element is composed of

Atoms• Atoms = more or less identical

building blocks for each element• Atomic symbol = one or two

letter chemical shorthand for each element

Carbon C Nitrogen NOxygen O Calcium CaHydrogen H Sodium Na

Atomic Structure• The nucleus consists of neutrons

and protons–Neutrons – have no charge and a mass of one atomic mass unit (amu)–Protons – have a positive charge and a mass of 1 amu

Atomic Structure• Electrons are found orbiting the

nucleus–Electrons – have a negative charge and 1/2000 the mass of a proton (0 amu)

Models of the Atom• Nucleus–Prontons (p+)–Neutrons (n0)

• Outside of nucleus–Electrons (e-)

Figure 2.1

Models of the Atom• Planetary

Model – electrons move around the nucleus in fixed, circular orbits

Figure 2.1

Models of the Atom• Orbital

Model – regions around the nucleus in which electrons are most likely to be found Figure 2.1

Identification of Elements• Atomic number – –equal to the number of protons that the atoms contain

• Mass number – –equal to the mass of the protons and neutrons – sum of the protons and neutrons

Identification of Elements• Atomic weight – –average of the mass numbers of all isotopes–Close to mass number of most abundant isotope–Atomic weight reflects natural isotope variation

Isotopes

• Isotope – atoms with same number of protons but a different number of neutrons

• Radioisotopes – atoms that undergo spontaneous decay called radioactivity

Radioactivity

• Rodioisotope – –Heavy isotope–Tends to be unstable–Decomposes to more stable isotope

• Radioactivity–Process of spontaneous atomic

Identification of Elements

Figure 2.2

Identification of ElementsIsotopes of Hydrogen

Figure 2.3

Molecules and Compounds• Molecule – two or more atoms held

together by chemical covalent bonds• Compound – two or more different

kinds of atoms chemically bonded together in ionic bonds

• Next time we will talk how these are chemically bonded

Mixtures and Solutions• Mixtures – two or more

components physically intermixed (not chemically bonded)

• 3 basic types–Solutions–Colloids–Suspensions

Solutions• Solutions – homogeneous

mixtures of components–Solvent – substance present in greatest amount–Solute – substance(s) present in smaller amounts

• May be gases, liquids, or solids

Solutions• Water is the body’s chief solvent

• Most solutions in the body are true solutions containing gases, liquids, or solids dissolved in water–True solutions are usually transparent

Concentration of Solutions• True solutions are described in

terms of their concentration (percent or molarity)

• Percent, or parts per 100 parts

• Molarity, or moles per liter (M)

Concentration of Solutions• To make a one-molar solution of

glucose – weigh out 1 mole of glucose and add enough water to make 1 liter of solution• A mole of an element or

compound is equal to its atomic or molecular weight (sum of atomic weights) in grams

• To find molecular weight of glucose C6 H12 O6– Glucose has 6 carbon, 12 hydrogen, & 6

oxygen atoms• To compute molecular weight of

glucose, look up the atomic weight of carbon, hydrogen and oxygen on a periodic table.

• Molecular weight of glucose is 180.156

Atom # of atoms

X Atomic weight

= Atomic weight

C 6 X 12.033 = 72066

H 12 X 1.008 = 12.096

O 6 X 15.999 = 95.994

180.456

Avogadro’s Number• One mole of any substance always

contains exactly the same number of solute particles6.02 X 1023

• So whether you weigh out 1 mole of glucose (180g) or water (18g) or methane (16g) or any other substance you will always have 6.02x1023 molecules of that substance

Colloids and Suspensions• Colloids, or emulsions, are

heterogeneous mixtures whose solutes do not settle out

• Suspensions are heterogeneous mixtures with visible solutes that tend to settle out

Mixtures Compared with Compounds• No chemical bonding takes place

in mixtures• Most mixtures can be separated

by physical means• Mixtures can be heterogeneous

or homogeneous• Compounds cannot be separated

by physical means• All compounds are homogeneous

QuizQuiz 1a over these lecture notes

Study guide check pages 24-28