CHAPTER 2 CHEMISTRY COMES ALIVE Section 2a
Feb 24, 2016
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