Bio 12 66% Water:________Unit B: Water, Acids/BasesThe Chemical Basis of Life

Standards1. ____________________________________________________________________________________

____________________________________________________________________________________2. ____________________________________________________________________________________

____________________________________________________________________________________3. ____________________________________________________________________________________

____________________________________________________________________________________4. ____________________________________________________________________________________

Nature’s Chemical LanguageChemicals play many more roles in life than _________________Making up our bodies, those of other organisms, and the physical environment

Living organisms are composed of about 25 chemical elementsAre essential to lifeMostly made up of carbon, hydrogen, oxygen and _____________________; make up the bulk of living matter (___________________)Are essential to life, but occur in minute amounts

Trace Elements are common additives to food and waterDietary deficiencies in trace elements can cause various ________________ conditionsTrace elements are essential to human health and may be added to food or water

Elements can combine to form compoundsA quick review!Chemical elements combine in fixed ratios to form compoundsMost of the compounds in living organisms contain at least ___________ to _____________ different elements, mainly C, H, O, N

- Eg. Vit A – made up of C, H, O- Eg. Proteins – ____, ____, ____, _____, ____

Atoms consist of protons, neutrons and electronsThe smallest particle of matter that still retains the properties of an element is an atomSubatomic Particles

- An atom is made up of ______________ and _____________ and is located in a central nucleus

- The nucleus is surrounded by ___________________ arranged in electron _______________

Atoms consist of protons, neutrons and electronsDifferences in Elements

- Atoms of each element are distinguished by a specific number of_____________

Isotopes- The number of neutrons in an atom may vary

- Some isotopes are ________________

Radioactive Isotopes can help or harm usLiving cells cannot distinguish between isotopes of the same element therefore they are taken up as per usualBecause radioactivity is easily detected, radioactive isotopes are useful as __________________ for monitoring the fate of atoms in living organisms (biological spies)

Isotopes and Medical DiagnosisRadioactive tracers are often used for diagnosis

- In combination with sophisticated imaging instruments- PET – _________________________________________ detects intense chemical activity in the body- Patient is injected with an isotope that emits subatomic particles called ________________- Positrons collide with electrons and give off ‘________________________’

Isotopes and DangersRadioactive isotopes have many beneficial uses

- But uncontrolled exposure to them can harm living organisms because any energy or radiation emitted can damage cells or more importantly ____________________

Electron arrangement determines the chemical properties of an atom- Electrons in an atom are arranged in shells, which may

contain different numbers of electrons- Atoms whose shells are not full tend to interact with other

atoms and ___________________________________________ electrons

- These interactions form __________________ bonds

Ionic bonds are attractions between ions of opposite charge- When atoms gain or lose

__________________________ charged atoms called ions are created

- An electrical attraction between ions with opposite charges results in an ______________________ bond

- Sodium and chloride ions bond to form sodium chloride, common table salt

Covalent bonds join atoms into molecules through electron sharing- In covalent bonds two atoms share one or more pairs of outer shell

electrons, forming __________________- Molecules can be represented in many ways - ______________________________ in oxygen

Unequal electron sharing creates polar molecules- A molecule is ____________________ when its covalently bonded atoms share electrons equally

because they have the ________________________________________- In a polar covalent bond electrons are shared unequally between atoms, creating a polar molecule- Gives water its ____________________________ status!

Hydrogen bonds are weak bonds important in the chemistry of life

- This attraction forms weak bonds called _______________________________

- Because oxygen is pulling electronegativity from hydrogen, this cause the H to be ___________________ attracting another oxygen

Bozeman – Water and Life (video)

Water’s Life-Supporting propertiesCrash Course – Liquid is Awesome (video)

Hydrogen bonds make liquid water cohesive- Due to __________________________________ water molecules

can move from a plant’s roots to its leaves- Insects can walk on water due to surface tension created by

_____________________ water molecules

Water’s hydrogen bonds moderate temperature- Water’s ability to store heat ________________ body temperature

and climate- Heat is the amount of energy associated with the movement of atoms and molecules- It takes a lot of energy to disrupt hydrogen bonds so water is able to

____________ a great deal of heat energy without a large increase in temperature

- Milder conditions near oceans because as oceans cool, they give off heat- ___________ of your body weight is water, this helps moderate your

internal temperature

Water’s hydrogen bonds moderate temperature- As water cools a slight drop in temperature releases a large amount of _________________

- A water molecule takes energy with it when it evaporates leading to _________________________ (humidity and sweat!)

Ice is less dense than liquid water- Hydrogen bonds _____________ molecules in

ice farther apart than in liquid water- Ice is therefore less dense than liquid water which causes it to

___________________- Floating ice protects lakes and oceans from freezing solid

Water is the solvent of life- Polar or charged solutes dissolve when water molecules surround

them, forming aqueous solutionsBozeman – Water: A polar Molecule (video)

The chemistry of life is sensitive to acidic and basic conditions- A compound that releases H+ ions in solution is an acid and

one that ______________ H+ ions in solution is a base- Acidity is measured on the pH scale from _______ (most

acidic) to ______ (most basic)- The pH of most cells is kept close to 7 (neutral) by buffers- Buffers are substances that _________ pH change

PH and Buffers VideosBozeman – pH and Buffers (Complex Chemistry)Crash Course – pH and pOH (complex chemistry)Crash Course - Buffers

Acid precipitation threatens the environment- Some ecosystems are threatened by

_____________________________________- Acid precipitation is formed when air pollutants from ______________ fossil fuels combine with water

vapor in the air to form _____________ and ________________ acids- These acids can kill trees and damage buildings

Chemical reactions change the composition of matter- In a chemical reaction reactants interact, atoms ________________, and products result

Chemical reactions change the composition of matter

- Living cells carry out thousands of chemical reactions that rearrange matter in __________________ ways