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Week 2-2 Basic chemistry

Week 2-2 Basic chemistry - Chapter 02 Basic Chemistry Basic...

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Unformatted text preview: Chapter 02 Basic Chemistry Basic Chemistry Basic 2 Outline Chemical Elements ŸAtoms ŸIsotopes ŸMolecules and Compounds Chemical Bonding ŸIonic and Covalent ŸHydrogen Properties of Water Acids and Bases Levels of biological organization Biosphere Biosphere All those regions of Earh’s waters, crust, and atmosphere in which organisms can exist Earh’ Ecosystem A community and its physical environment Community The populations of all species occupying the same area Population A group of individuals of the same kind (species) occupying a given area given Multicelled organism An individual composed of specialize, interdependent cells most often organized in tissues, organs, and organ systems Two or more organs interacting chemically, physically, or both in ways that contribute to survival of the whole organism in Tissue An organized group of cells and surrounding substances functioning together in a specialized activity functioning Cell Smallest unit having the capacity to live and reproduce, independently or as part of a multicelled organism independently Organelle Inside all cells except bacteria, a membrane-bound sac or compartment for a separate, specialized task membrane- Molecule A unit in which two or more atoms of the same element or different ones are bonded together different Atom Smallest unit of an element (a fundamental substance) that still retains the properties of that element Subatomic particle An electron, proton, or neutron; one of the three major particles of which atoms are composed particles Living matters Organ system Bohr Models of Atoms 6 Chemical foundations for Cells • Atom: the small particle retained the properties of an element • An atom consists of proton(s), electron(s), and neutron(s) Electron Oxygen atom H20 Hydrogen atom Proton Animation: Atomic structure (Chapter 2-1, Figure 2). 7 Basic Chemistry Basic 8 Atomic Structure Atoms - Smallest particles of elements Atoms composed of three types of subatomic particles ŸProtons - Positive charge - In nucleus Helium ŸNeutrons - Neutral charge - Also found in nucleus ŸElectrons - Negatively charge - Orbit nucleus Periodic Table (Revisited) Vertical columns indicate number of electrons in outermost shell I 1 9 VIII 2 Horizontal periods indicate total number of electron shells 1 2 3 4 H 1.008 3 II 4 III 5 IV 6 V 7 VI 8 VII 9 He 4.003 10 Li 6.941 11 22.99 19 Be 9.012 12 24.31 20 40.08 B 10.81 13 26.98 21 69.72 C 12.01 14 N 14.01 15 O 16.00 16 F 19.00 17 35.45 25 79.90 Ne 20.18 18 39.95 26 83.60 Na Mg Al K 39.10 Si 28.09 22 72.59 P 30.97 23 74.92 S 32.07 24 78.96 Cl Ar Ca Ga Ge As Se Br Kr Basic Chemistry Basic 10 Periodic Table Elements grouped in periodic table based on characteristics ŸVertical columns = groups; chemically similar ŸHorizontal rows = periods; larger and larger I 1 1H 1.008 II 4 9.012 12 24.31 20 40.08 2 Groups He III IV V VI VII 4.003 5 6 7 8 9 10 VIII Periods 2 Li Be B 6.941 11 22.99 19 39.10 10.81 13 26.98 21 69.72 3 C 12.01 14 28.09 22 72.59 N 14.01 15 O 16.00 16 F 19.00 17 35.45 25 79.90 Ne 20.18 18 39.95 26 83.60 3 Na Mg Al Si P 30.97 23 74.92 S 32.07 24 78.96 Cl Ar 4 K Ca Ga Ge As Se Br Kr Basic Chemistry Basic 11 Chemical Elements Matter: ŸRefers to anything that has mass and occupies space ŸOnly 92 naturally occurring fundamental types of matter – 92 Elements Organisms composed primarily (98%) of only six elements ŸCarbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur ŸCHNOPS Basic Chemistry Basic 12 Elements and Compounds Molecule - Two or more atoms bonded together ŸIf all atoms in molecule are of the same element - Material is still an element - O2, H2, N2, etc. ŸIf at least one atom is from a different element - Material formed is a compound - CO2, H2O, C6H12O6, etc. - Characteristics dramatically different from constituent elements From Atoms to Molecules • Two or more atoms bond form a molecule Na Na+ Na-Cl NaCl Cl Cl2N N-N N 2 covalent bond H+ ionic bond H+ • Three kinds of bond: – Ionic bond – Covalent bond – Hydrogen bond C2+ N3- Animation: CH4 ionic bond (Chapter 3-1, Figure 1), C2H6 covalent bond ( Figure 2), 13 Types of Bonds: Ionic Bonding Basic Chemistry Basic 14 Ionic Bonds - Atoms “want” 8 electrons in outer shell have < 4 outers, desire to donate them w If have > 4 outers, desire to receive more w If ŸConsider two elements from opposite ends of periodic table - Element from right side: 7 electrons in outer shell w “Desperately wants” one more (7+1=8) w Has - Element from left side: only 1 electron in outer shell w “Desperately wants” to donate it (1-1=0=8) w Has Types of Bonds: Ionic Bond Example Sodium: Ÿ From left end Ÿ Has 1 outer electron Basic Chemistry Basic 15 Chlorine: Ÿ From right end of table Ÿ Has 7 outer electrons In reaction, Na completely gives up its outer electron to Cl Ÿ Na now a positive ion and Cl a negative ion Ÿ Dissimilar charges now bind ions together Ÿ Forms sodium chloride - An ionic compound - NaCl table salt) Formation of Sodium Chloride 16 Types of Bonds: Covalent Bonds Basic Chemistry Basic 17 When atoms are horizontally closer together in the periodic table Ÿ The electrons are not permanently transferred from one atom to the other like in NaCl Ÿ A pair of electrons from the outer shell will “time share” with one atom and then the other Ÿ This also causes the atoms to remain together Ÿ Known as covalent bonding Sometimes two par of electrons are shared between atoms – a double covalent bond Covalently Bonded Molecules 18 Types of Bonds: Hydrogen Bonds Basic Chemistry Basic 19 Water (H2O or H–O–H) is a polar molecule ŸElectrons spend more time with O than H’s ŸH’s become slightly +, O slightly – When polar molecules are dissolved in water ŸThe H’s of water molecules are attracted to the of negative parts of the solute molecules negative ŸResults in a weak bond – the hydrogen bond ŸEasily broken, but many together can be quite strong Water Molecule 20 Hydrogen Bonding 21 The Chemistry of Water: Heat Capacity Water has a high heat capacity Basic Chemistry Basic 22 Ÿ Temperature = rate of vibration of molecules Ÿ Apply heat to liquid - Molecules bounce faster - Increases temperature Ÿ But, when heat applied to water - Hydrogen bonds restrain bouncing - Temperature rises more slowly per unit heat - Water at a given temp. has more heat than most liquids Properties of Water: Heat of Vaporization High heat of vaporization Basic Chemistry Basic 23 Ÿ To raise water from 98 to 99 ºC; ~1 calorie Ÿ To raise water from 99 to 100 ºC; ~1 calorie Ÿ However, large numbers of hydrogen bonds must be broken to evaporate water Ÿ To raise water from 100 to 101 ºC; ~540 calories! This is why sweating (and panting) cools Ÿ Evaporative cooling is best when humidity is low because evaporation occurs rapidly Ÿ Evaporative cooling works poorest when humidity is high because evaporation occurs slowly Evaporative Cooling Basic Chemistry 24 Basic of Animals Properties of Water: Water as a Solvent Solutions consist of: Basic Chemistry Basic 25 ŸA solvent (the most abundant part) and ŸA solute (less abundant part) that is dissolved in the solvent ŸNa+ ŸCl- Ionic compounds dissociate in water - Attracted to negative (O) end of H2O - Each Na+ completely surrounded by H2O - Attracted to positive (H2) end of H2O - Each Cl- completely surrounded by H2O Properties of Water: Heat of Fusion Heat of fusion (melting) Basic Chemistry Basic 26 ŸTo raise ice from -2 to -1 ºC; ~1 calorie ŸTo raise water from -1 to 0 ºC; ~1 calorie ŸTo raise water from 0 to 1 ºC; ~80 calories! This is why ice at 0 ºC keeps stuff cold MUCH longer than water at 1 ºC This is why ice is used for cooling ŸNOT because ice is cold ŸBut because it absorbs so much heat before it will warm by one degree Heat Content of Water Basic Chemistry 27 Basic at Various Temperatures Properties of Water: Uniqueness of Ice Basic Chemistry Basic 28 Frozen water less dense than liquid water ŸOtherwise, oceans and deep lakes would fill with ice from the bottom up ŸIce acts as an insulator on top of a frozen body of water ŸMelting ice draws heat from the environment Density of Water at Various Temperatures 29 A Pond in Winter 30 Water as a Transport Medium 31 pH of Water: Acids Basic Chemistry Basic 32 Acids ŸDissociate in water and release hydrogen ions (H+) ŸSour to taste ŸHydrochloric acid (stomach acid) is a gas with symbol HCl - In water, it dissociates into H+ and Cl- Dissociation of HCl is almost total, therefore it is a strong acid pH of Water: Bases Basic Chemistry Basic 33 Bases: ŸEither take up hydrogen ions (H+) or release hydroxide ions (OH-) ŸBitter to taste ŸSodium hydroxide (drain cleaner) is a solid with symbol NaOH - In water, it dissociates into Na+ and OH- Dissociation of NaOH is almost total, therefore it is a strong base Basic Chemistry Basic 34 pH Scale pH scale used to indicate acidity and alkalinity pH of a solution. of ŸValues range from 0-14 - 0 to <7 = Acidic - 7 = Neutral - >7 to 14 = Basic (or alkaline) ŸLogarithmic Scale - Each unit change in pH represents a change of 10X - pH of 4 is 10X as acidic as pH of 5 - pH of 10 is 100X more basic than pH of 8 The pH Scale 35 Basic Chemistry Basic 36 Review Chemical Elements ŸAtoms ŸIsotopes ŸMolecules and Compounds Chemical Bonding ŸIonic and Covalent ŸHydrogen Properties of Water Acids and Bases Ending Slide Chapter 02 Basic Chemistry ...
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