02_Lecture_Presentation_KC

Slide 1: 

Give an example of solid matter. 2. Give an example of liquid matter. 3. Give an example of gaseous matter. 4. Is all matter visible? 5. Does all matter take up space?

Chapter 2 : 

Chapter 2 Essential Chemistry for Biology

SOME BASIC CHEMISTRY : 

SOME BASIC CHEMISTRY Take any biological system apart, and you eventually end up at the chemical level. Matter is anything that occupies space and has mass. Matter is found on the Earth in three physical states: Solid Liquid Gas

Slide 4: 

H Rb K Na Li Fr Cs Sr Ca Mg Be Ra Ba Y Sc Ac La Zr Ti Rf Hf Nb V Db Ta Mo Cr Sg W Tc Mn Bh Re Ru Fe Hs Os Rh Co Mt Ir Pd Ni Uun Pt Xe Kr Uuo Rn Ag Cu Uuu Au Cd Zn Uub Hg Ar Ne In Ga Tl Al B Sn Ge Uuq Pb Si C Sb As Bi P N Te Se Uuh Po S O I Br At Cl F He Th Ce Pa Pr U Nd Np Pm Pu Sm Am Eu Lr Lu Cm Gd Bk Tb Cf Dy Es Ho Fm Er Md Tm No Yb 6 C 12 Figure 2.1

Slide 5: 

Twenty-five elements are essential to life. Four elements make up about 96% of the weight of the human body: Oxygen Carbon Hydrogen Nitrogen

Atoms : 

Atoms Each element consists of one kind of atom. An atom is the smallest unit of matter that still retains the properties of an element Atoms are composed of subatomic particles. Central core consists of 2 kinds of particles: Proton, + charge Neutron, no electrical charge All atoms have the same number of protons. # of protons = atomic number + charge is balanced by an = number of – charged particles called electrons

Slide 7: 

The Atom ATOM: Simplest particle of an element that retains all of the properties of that element Atomic Number= # of Protons Atomic Mass Chemical Symbol

Slide 8: 

Nucleus Protons Neutrons Electrons Nucleus Cloud of negative charge 2 electrons 2 2 2 Figure 2.4

Slide 9: 

Elements differ in the number of subatomic particles in their atoms. The number of protons, the atomic number, determines which element it is. An atom’s mass number is the sum of the number of protons and neutrons. Mass is a measure of the amount of matter in an object.

Chemical Bonding : 

Chemical Bonding Inert elements (last column on periodic table) have their outermost energy level fully occupied by electrons Reactive elements do not have their outermost energy level fully occupied by electrons Octet rule – except for the first shell which is full with two electrons, atoms interact in a manner to have eight electrons in their valence shell

Isotopes : 

Isotopes Isotopes are alternate mass forms of an element. Isotopes have the same number of protons and electrons, but they have a different number of neutrons.

Slide 12: 

The nucleus of a radioactive isotope decays, giving off particles and energy. Radioactive isotopes have many uses in research and medicine. They can be used to determine the fate of atoms in living organisms. They are used in PET scans to diagnose heart disorders and some cancers.

Electron Arrangement and the Chemical Properties of Atoms : 

Electron Arrangement and the Chemical Properties of Atoms Electrons determine how an atom behaves when it encounters other atoms. Electrons orbit the nucleus of an atom in specific electron shells. The farther an electron is from the nucleus, the greater its energy. The number of electrons in the outermost shell determines the chemical properties of an atom. © 2010 Pearson Education, Inc.

Slide 14: 

First electron shell can hold 2 electrons Outer electron shell can hold 8 electrons Hydrogen H Atomic number = 1 Carbon C Atomic number = 6 Nitrogen N Atomic number = 7 Oxygen O Atomic number = 8 Electron Figure 2.5

Chemical Bonding and Molecules : 

Chemical Bonding and Molecules Elements can combine to form compounds by action of electrons. Compounds are substances that contain two or more elements in a fixed ratio. Common compounds include NaCl (table salt) H2O (water) Chemical reactions enable atoms to give up or acquire electrons to complete their outer shells. Chemical reactions usually result in atoms Staying close together Being held together by chemical bonds

Ionic Bonds : 

Ionic Bonds When an atom loses or gains electrons, it becomes electrically charged. Charged atoms are called ions. Ionic bonds are formed between oppositely charged ions.

Covalent Bonds : 

Covalent Bonds A covalent bond forms when two atoms share one or more pairs of outer-shell electrons. Atoms held together by covalent bonds form a molecule. The number of covalent bonds an atom can form is equal to the number of additional electrons needed to fill its outer shell. Animation: Covalent Bonds

Slide 18: 

Electron sharing Atoms joined into a molecule via covalent bonds Figure UN2-7

Slide 19: 

Name molecular formula Hydrogen gas H2 Oxygen gas O2 Methane CH4 Electron configuration Structural formula Space-filling model Ball-and-stick model Single bond a pair of shared electrons Double bond two pairs of shared electrons Figure 2.7

Hydrogen Bonds : 

Hydrogen Bonds Water is a compound in which the electrons in its covalent bonds are shared unequally. This causes water to be a polar molecule, one with opposite charges on opposite ends. Animation: Water Structure

Slide 21: 

H H O slightly  slightly  slightly – Figure UN2-2

Slide 22: 

The polarity of water results in weak electrical attractions between neighboring water molecules. These interactions are called hydrogen bonds.

Water’s Life-Supporting Properties : 

Water’s Life-Supporting Properties Life on Earth began in water and evolved there for 3 billion years. Modern life remains tied to water. Your cells are composed of 70%–95% water. The abundance of water is a major reason Earth is habitable. The polarity of water molecules and the hydrogen bonding that results explain most of water’s life-supporting properties. Water molecules stick together. Water has a strong resistance to change in temperature. Frozen water floats. Water is a common solvent for life.

The Cohesion of Water : 

The Cohesion of Water Water molecules stick together as a result of hydrogen bonding. This is called cohesion. Cohesion is vital for water transport in plants.

Slide 25: 

Surface tension is the measure of how difficult it is to stretch or break the surface of a liquid. Hydrogen bonds give water an unusually high surface tension.

How Water Moderates Temperature : 

How Water Moderates Temperature Because of hydrogen bonding, water has a strong resistance to temperature change. Water can absorb and store large amounts of heat while only changing a few degrees in temperature.

The Biological Significance of Ice Floating : 

The Biological Significance of Ice Floating When water molecules get cold enough, they move apart, forming ice. A chunk of ice has fewer molecules than an equal volume of liquid water. Ice floats because it is less dense than the liquid water around it. If ice did not float, ponds, lakes, and even the oceans would freeze solid. Life in water could not survive if bodies of water froze solid.

Slide 28: 

Hydrogen bond Liquid water Ice Figure 2.13

Water as the Solvent of Life : 

Water as the Solvent of Life A solution is a liquid consisting of a homogeneous mixture of two or more substances. The dissolving agent is the solvent. The dissolved substance is the solute.

Acids, Bases, and pH : 

Acids, Bases, and pH A chemical compound that releases H+ to solution is an acid. A compound that accepts H+ and removes it from solution is a base. To describe the acidity of a solution, chemists use the pH scale. Buffers are substances that resist pH change. Buffers Accept H+ ions when they are in excess Donate H+ ions when they are depleted

Slide 31: 

Basic solution Neutral solution Acidic solution Oven cleaner Household bleach Human blood Pure water Grapefruit juice, soft drink Lemon juice, gastric juice Household ammonia Milk of magnesia Seawater Tomato juice Urine pH scale 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Increasingly acidic greater H concentration Increasingly basic lower H concentration Neutral [H+]  [OH–] Figure 2.16

Slide 32: 

Basic solution Neutral solution Acidic solution Figure 2.16a