Chemistry

the dirty little secret about Biology

Chemistry

Chemicals are the stuff that make up– our bodies,– the bodies of other organisms, and– the physical environment.

(wait, isn’t that Biology?)

© 2012 Pearson Education, Inc.

Water

Life’s chemistry is tied to water.– Life first evolved in water.– All living organisms require water.– The chemical reactions of your body occur in

cells consisting of 70–95% water.

© 2012 Pearson Education, Inc.

Matter

• anything that occupies space and has mass• composed of elements

– cannot be broken down into other substances– 92 in nature; scientists have created 26 more

• created elements too unstable to occur naturally

• you ARE chemistry• chemistry is your friend!

© 2012 Pearson Education, Inc.

Atoms

• smallest unit of matter that still retains properties of that element (fxnal unit of matter)– nucleus

• protons (positive charge)• neutrons (no charge)

– orbital shell• electrons (negative charge and hardly any weight)

– opposites attract

© 2012 Pearson Education, Inc.

Figure 2.3A

Helium

2e

Nucleus

Electroncloud

2

2

2

Protons

Neutrons

Electrons

Mass number 4

http://www.design564.com/wp-content/uploads/2010/09/periodic_table_of_elements1.jpg

http://www.google.com/imgres?imgurl=http://www.classzone.com/books/earth_science/terc/content/investigations/es0501/images/es0501_p6_readinginfo_b.gif&imgrefurl=http://www.classzone.com/books/earth_science/terc/content/investigations/es0501/es0501page06.cfm&usg=__Px06U8z6IBfQlwNWxuoI82oO_k4=&h=410&w=550&sz=30&hl=en&start=1&zoom=1&tbnid=tKy18DAObylfeM:&tbnh=99&tbnw=133&ei=4hODTrKMM8S5tgemvYTkAQ&prev=/search%3Fq%3Dperiodic%2Btable%2Bwith%2Bexplanation%26hl%3Den%26gbv%3D2%26tbm%3Disch&itbs=1

http://www.design564.com/wp-content/uploads/2010/09/periodic_table_of_elements1.jpg

Figure 2.3B

Carbon

Electroncloud

Nucleus

Protons

Neutrons

Electrons

Mass number 12

6e

6

6

6

http://www.design564.com/wp-content/uploads/2010/09/periodic_table_of_elements1.jpg

http://faculty.weber.edu/bdattilo/images/tim_isoth.gif

http://terra.dadeschools.net/Books/Biology/BiologyExploringLife04/0-13-115075-8/text/chapter4/04images/04-05.gif

Isotopes: Medical Uses

Living cells cannot distinguish between isotopes of the same element.– Therefore, radioactive compounds in

metabolic processes can act as tracers.– This radioactivity can be detected by

instruments.– Using these instruments, the fate of

radioactive tracers can be monitored in living organisms.

© 2012 Pearson Education, Inc.

Chemical Bonds

• electrons: the only part of an atom that interact• arranged in shells around the nucleus• have one, two or three electron shells

– have to fill the 1st shell then get a 2nd shell– have to fill the 2nd shell, then get a 3rd shell

http://www.btinternet.com/~chemistry.diagrams/electron-shells.gif

© 2012 Pearson Education, Inc.

Figure 2.5_1

Hydrogen

Lithium

Sodium

Beryllium

Magnesium

Boron

Aluminum

Carbon

Silicon

Nitrogen

Phosphorus

Oxygen

Sulfur

Fluorine

Chlorine

Helium

Neon

Argon

Chemical Bonds

• # of shells determined by # of protons• atoms want the outermost shell to be filled

=STABILITY

Figure 2.1

Sodium Chlorine Sodium chloride

Chemical Bonds: 3 Types• Ionic: gaining OR losing of electrons

NaCl excellent exampleNa+ has 1 e- in its outer shell (how many needed to be stable?)Cl- has 7 e- in its outer shell(how many needed to be stable?)

http://www.google.com/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/4/47/Electron_shell_011_sodium.png&imgrefurl=http://la.wikipedia.org/wiki/Fasciculus:Electron_shell_011_sodium.png&usg=__4F00tRgPNZDAYfGI9xN5lscHFWs=&h=1835&w=1678&sz=105&hl=en&start=1&zoom=1&tbnid=MYjB82CBG92KJM:&tbnh=150&tbnw=137&ei=oyODTuShJ-Xt0gH_ovGcAQ&prev=/images%3Fq%3Dsodium%2Belectron%2Bshells%26um%3D1%26hl%3Den%26gbv%3D2%26tbm%3Disch&um=1&itbs=1

http://upload.wikimedia.org/wikipedia/commons/5/56/Electron_shell_017_chlorine.png

Figure 2.7A_s2

Transfer of electron

NaSodium atom

ClChlorine atom

Na

Sodium ionCl

Chloride ion

Sodium chloride (NaCl)

Now both Na+ and Cl- have filled their outer shells = STABILITY!!!

they are ALSO both charged now b/c they have an electron/proton imbalance

Ionic Bonds: OPPOSITES attract

WEAK: toss in water and dissolve-why?

http://web.virginia.edu/Heidi/chapter2/chp2.htm

Ionic Bonds

• Synonyms:– salt– electrolyte

• Similar to ‘dating’

• Ca++ means what?• PO4

3- means what?

Covalent Bonds

• e- are shared: they orbit around nuclei of both atoms involved in the bond

• very strong bond: – takes NRG to create– releases NRG when broken

• MARRIAGE!!!

http://alevelnotes.com/Bonding/130

http://www.school-for-champions.com/chemistry/bonding_types.htm

http://www.tutorvista.com/content/chemistry/chemistry-i/chemical-bonding/triple-covalent-bond.php

Covalent Bonds

• two or more atoms joined together= MOLECULE

• two or more types of atoms joined together= COMPOUND

all compounds are molecules, BUT not all molecules are compounds

Table 2.6

http://www.school-for-champions.com/chemistry/bonding_types.htm

nonpolar: equal sharing of e-

Figure 2-5 Polar Covalent Bonds and the Structure of Water

Hydrogen atom

Hydrogen atom

Oxygen atom2

© 2012 Pearson Education, Inc.

Polar: UNequal sharing of e- due to difference in pull from nucleus

Hydrogen Bonds: weak but IMPORTANT!!!

http://www.elmhurst.edu/~chm/vchembook/162othermolecules.html http://www.dna-sequencing-service.com/dna-sequencing/dna-hydrogen-bonds-2/

Chemical Reactions

• Interactions between atoms– making bonds (stores NRG)– breaking bonds (releases NRG)

• chemical rxns do not create or destroy matter– rearrange matter– rxns of life generally require enzymes

• NRG not created or destroyed