Bio 12 Name: ____________Unit B: Water, Acids/Bases

Chapter 2: The Chemical Basis of Life

Standards1. ____________________________________________________________________________________

____________________________________________________________________________________2. ____________________________________________________________________________________

____________________________________________________________________________________3. ____________________________________________________________________________________

____________________________________________________________________________________4. ____________________________________________________________________________________

Nature’s Chemical Language The rattlebox mothProduces chemicals important for _______________and _________________

- Defensive chemicals from plants that they eatThe compound produced during mating

- Allows the moths to communicate using chemicals- Sperm, nutrients and alkaloid Protection and life insurance!

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

2.1 - 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

2.2 – 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

2.3 – 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 – ____, ____, ____, _____, ____

2.4 – 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 _____________ - Located in a central nucleus

- The nucleus is surrounded by ___________________- Arranged in electron _______________

2.4 – 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

- Variant forms of an element are called ______________ - Some isotopes are ________________

2.5 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 Basic ResearchBiologists often use radioactive tracers

- To follow molecules as they undergo chemical changes in an organismPlant researchers have used them to study photosynthesis

- Traced the isotope of _______________ and found it ended up in a ______________ molecule

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

____________________

2.6 – Electron arrangement determines the chemical properties of an atomElectrons 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

2.7 - Ionic bonds are attractions between ions of opposite chargeWhen atoms gain or lose __________________________

- Charged atoms called ions are createdAn electrical attraction between ions with opposite charges

- Results in an ______________________ bondSodium and chloride ions

- Bond to form sodium chloride, common table salt

2.8 - Covalent bonds join atoms into molecules through electron sharingIn covalent bonds

- Two atoms share one or more pairs of outer shell electrons, forming __________________- Molecules can be represented in many ways - ______________________________ in oxygen

2.9 - 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!

2.10 - 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 LifeWater’s Life-Supporting propertiesCrash Course – Liquid is Awesome

2.11 - 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

2.12 - Water’s hydrogen bonds moderate temperatureWater’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

2.12 - Water’s hydrogen bonds moderate temperatureAs 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!

2.13 - Ice is less dense than liquid waterHydrogen bonds _____________ molecules in ice

- Farther apart than in liquid waterIce is therefore less dense than liquid water

- Which causes it to ___________________Floating ice

- Protects lakes and oceans from freezing solid

2.14 Water is the solvent of lifePolar or charged solutes

- Dissolve when water molecules surround them, forming aqueous solutions

Bozeman – Water: A polar Molecule

2.15 The chemistry of life is sensitive to acidic and basic conditionsA 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

2.16 - Acid precipitation threatens the environmentSome ecosystems are threatened by _____________________________________Acid precipitation is formed when air pollutants from ______________ fossil fuels

- Combine with water vapor in the air to form _____________ and ________________ acidsThese acids

- Can kill trees and damage buildings

2.17 Chemical reactions change the composition of matterIn a chemical reaction

- Reactants interact, atoms ________________, and products result

2.17 Chemical reactions change the composition of matterLiving cells carry out thousands of chemical reactions

- That rearrange matter in __________________ ways