Chemistry for Life Chapter 2 Dr Bill Stafford 2016

State Standards CLE 3210.1.2 Distinguish among the structure and function of the four major organic macromolecules found in living things. CLE 3210.1.3 Describe how enzymes regulate chemical reactions in the body.

I Can Statements I Can Statements 1. I can list and describe the three parts of the atom. 2. I can relate acidity and basicness to the pH scale. 3. I can discuss chemical structure of water and relate it to the role in living things.

Chemistry for Life – Chapter 6 Elements – substances that cannot be broken down into simpler substances Examples – Hydrogen Carbon Oxygen Nitrogen

Chemistry for Life – Chapter 6 Element 90 occur naturally – 25 essential for living organisms 4 elements make up 96% of the human body – CHON 1. Carbon – C 2. Hydrogen – H 3. Oxygen – O 4. Nitrogen – N 1-2 letter abbreviation Trace elements – found in small amounts in living organisms

Chemistry for Life – Chapter 6 Elements Elements come into plants through the roots. Elements come into animals from the food they eat.

Chemistry for Life – Chapter 6 Atoms – smallest particle that has the characteristics of the element Examples – Hydrogen and oxygen A. Parts of an atom 1. Nucleus – center of the atom a. Proton – has a positive (+) charge – the number of protons defines the element – atomic number b. Neutron – has no charge – neutral – usually the same number as protons

Chemistry for Life – Chapter 6 Atoms A. Parts of an atom 2. Electron cloud – made up of electrons that have little mass and a negative (-) charge B. Elements usually have an equal number of protons and electrons. This gives the atom no net charge. Examples: oxygen - 8 protons and 8 electrons hydrogen – 1 proton and 1 electron carbon – 6 protons and 6 electrons

Summary of Subatomic Particles:   Particle Name Location Charge Mass Electron Orbitals -1 ~0 Proton Nucleus +1 1 Neutron No Charge

Chemistry for Life – Chapter 6 Atoms C. Atomic mass – total number of protons and neutrons Examples: carbon 6 protons + 6 neutrons = atomic weight of 12 Example: Carbon 6 protons and 6 neutrons Atomic number – 6 (6 protons) Atomic mass – 12 ( 6 protons and 6 neutrons) All atoms with 6 protons are always carbon atoms

Atoms differ in __________ of _______, ________,& _______ NUMBERS PROTONS NEUTRONS ELECTRONS Image from: http://www.uic.edu/classes/bios/bios100/summer2004/lect02.htm

Periodic Table Notation: It is the number of protons an element has which determines what element it is. Carbon = 12 Hydrogen = 1 Oxygen = 16 Nitrogen = 17 Neutral atoms have EQUAL numbers of protons (+) and electrons (-)

Chemistry for Life – Chapter 6 Isotopes – Atoms of an element with a different number of neutrons. Examples: C-12 – 6 protons and 6 neutrons – atomic weight of 12 C-14 – 6 protons and 8 neutrons – atomic weight of 14

Chemistry for Life – Chapter 6 Compounds – 2 or more different atoms chemically joined by chemical bonds. A. Examples: H2O and CO2 B. The compound has different properties than either element (atom) that makes it up – H2O (water) is liquid and hydrogen (H) and oxygen (O) are gases Molecule -2 or more atoms chemically joined – can be different atoms or the same – O2 or H2O – I will use both words – compound and molecule

ATOMS CAN ______TOGETHER TO _____________________ JOIN MAKE MOLECULES Ex: Joining 2 HYDROGEN atoms with 1 OXYGEN atom makes one ______ molecule. WATER A _______________ tells _________ of and __________ atoms are in a molecule EX: ________ what kind chemical formula how many H2O http://www.lsbu.ac.uk/water/molecule.html

ELECTRON / ENERGY LEVEL RULES: Atoms seek to have a “full” outermost energy level. All chemical formulas and reactions happen to accomplish this Filled outer energy levels mean the substance is inert or stable (won’t react)

Chemistry for Life – Chapter 6 Chemical bonds – What holds compounds together A. Covalent bonds – the atoms share electrons to fill the outer shells  leads to a more stable state Examples: - fats, carbohydrates, proteins, water Very common in living organisms B. Ionic bonds – one atom receives an electron to get a negative charge and one atom gives up an electron to get a positive charge – the atoms are held together by their opposite electrical charges Examples: Table salt – NaCl Very rare in living organisms

Interactions of matter: Atoms interact through the process of chemical bonding. Bonding is determined by the number of electrons found in the outermost energy level of an atom (valence electrons) Bonding Involves the transfer & sharing of electrons between atoms. Covalent (sharing of electrons) Ionic (transfer of electrons)

Ionic Bonds: Table salt (sodium chloride) forms by ionic bonding Sodium loses 1 electron = +1 ion (Na+1) Chlorine gains 1 electron = -1 ion (Cl-1) Compound is NaCl

Summary of Ionic & Covalent Bonds

Chemistry for Life – Chapter 6 Ions – electrically charged atoms – give up or acceppts an electron A. Negative ion (-) – anion – accepts an electron B. Positive ion (+) – cation – gives up an electron

KEY CONCEPT Water’s unique properties allow life to exist on Earth.

Water Importance of water 1. Solvent of living organisms 2. Material transport – blood in animals and sap in plants 3. Makes up 70-95% 0f all organisms

Life depends on hydrogen bonds in water. Water is a polar molecule. Polar molecules have slightly charged regions. O H _ + Nonpolar molecules do not have charged regions. Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.

Water (continued) Water is a polar molecule – a compound with unequal distribution of electrical charge 1. Electrons (negative) closer to oxygen due to 8 (+) protons in nucleus 2. Positive charge on hydrogen side and negative charge on oxygen side 3. Forms weak hydrogen bonds – attraction of opposite charges

Hydrogen bonds are responsible for four important properties of water. high specific heat cohesion Adhesion Ice floats – less dense

Water (continued) Important properties of water due to polarity of water molecule 1. Cohesion and adhesion  capillary action  transport of water from roots to leaves 2. Surface tension – allows things to float 3. Resists temperature change – homeostasis 4. Water expands when it freezes  ice floats  makes soil

Chemistry for Life – Chapter 6 Mixture and solutions A. Mixture – a combination of substances where each substance retains (keeps) its own properties and can be easily separated. B. Solution – Two or more substances that are mixed evenly together – solution has new properties different than either ingredient – hard to separate 1. Solvent – dissolving substance – usually water 2. Solute – Substance that is dissolved – usually a solid The concentration of each is critical

“Like dissolves like” HYDROPHILIC ____________________ means “water loving” _________ groups/molecules try to _________ and touch water or __polar___molecules be near other polar Water makes a great solvent in living things because so many molecules found in living things are polar or have a charge. http://www.makash.ac.il/h_school/hst/hstsb/chem/luach/dissolve.jpg

“Like dissolves like” HYDROPHOBIC http://egullet.com/imgs/egci/nonstocksauce/nons1.JPG “Like dissolves like” HYDROPHOBIC _________________ means “water fearing” ___________ groups/molecules try to _________ other __________ molecules and __________ ________ molecules NON-polar be near NON-polar away from polar Oil based paints dissolve in solvents such as turpentine . . . not water.

Chemistry for Life – Chapter 6 Acids and bases A. Acids – results in excess of H+ ions in water Examples B. Bases – results in excess of OH- ions or decrease of H+ ions C. pH scale – shows acidity or basic quality of substance 1. Below 7 is acidic 2. 7 is neutral – not acidic or basic 3. Above 7 is basic

Chemistry for Life – Chapter 6 Acids and bases C. pH scale A substance with an extreme pH close to 1 or 14 is very caustic and damaging

Hydrogen Ions (H+) More H+ = more acidic H+ acidic http://www.guardiantrader.com/images/ph_scale.gif The number of ____ ions determine how _______ a solution will be. H+ acidic More H+ = more acidic