Chemistry the dirty little secret about Biology
Dec 26, 2015
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