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Scientists devised experiments to shed light on whether different fish species of the same genus compete in their natural habitat. They constructed 12.

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Presentation on theme: "Scientists devised experiments to shed light on whether different fish species of the same genus compete in their natural habitat. They constructed 12."— Presentation transcript:

1 Scientists devised experiments to shed light on whether different fish species of the same genus compete in their natural habitat. They constructed 12 ponds, identical in chemical composition and physical characteristics. Then they released the following individuals into each pond: Ponds 1,2,3Species A300 per pond Ponds 4,5,6Species B300 per pond Ponds 7,8,9Species C300 per pond Ponds 10,11,12Species A,B,C300 of each per pond Does this experimental design take into consideration all factors that can affect the outcome? If not, how would you modify it?

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3 Carbon Hydrogen Oxygen Nitrogen } 96% of life

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5 = Number of protons

6 = Number of protons + Number of neutrons

7 Isotopes occur because of variations in neutron number (proton number is always the same)

8 Spontaneous decay of nucleus Emits energy Used as radioactive tags in-medicine.html

9 Located in energy levels (shells) Shells closest to nucleus are lower energy levels Shells farther away are higher energy levels

10 Chemical properties depend on the number of valence electrons

11 Only 2 electrons per orbital

12 Ions = charged particles Cations = + Anions = - Ionic bonding Cations and anions attract Forms salts 020.html

13 Covalent bonds Atoms share valence electrons 020.html

14 Polar and Nonpolar Covalent Bonding Polar – electrons are shared unequally Charge difference

15 Polar and Nonpolar Covalent Bonding Nonpolar – electrons are shared equally No charge difference

16 Weak attraction between H and electronegative atom Found in: H 2 O Proteins Nucleic Acids Easily Broken

17 ical%20anamations.html

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21 Cohesion (water molecules cling to each other) Causes surface tension

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23 Adhesion (water molecules cling to other molecules) Allows for “capillarity” Water travels upward through vascular tissue

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27 Temperature Stabilization heat does not immediately change temperature

28 Evaporative cooling As H2O evaporates, remaining liquid area is cooler Molecules with more heat energy leave as vapor

29 Solvent properties Polarity allows water to “tear apart” molecules

30 Water dissociation

31 Water has neutral pH because of equilibrium between H+ and OH- Acids – proton (H+) donors Bases (alkaline fluids) – proton acceptors (OH-)

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33 Buffers – regulate pH by countering slight changes Accept H+ when it is in excess Donate H+ when they are depleted chemistry/essentialchemistry/f lash/buffer12.swf

34 Explain, with reference to its properties, the significance of water as a coolant, a means of transport and as a habitat.


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