Giving and receiving electrons. Negative (anion) or positive (cation). Strong forces of attraction called ionic bonds hold the oppositely charged ions together.
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Covalent bonding
Sharing electrons. Form very strong bonds, usually neutral but occasionally slightly polarised. Electrons are not evenly shared, creates dipole (slighty negative and positive parts). Polar molecule - common if one or more hydrogen atoms are involved
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Why are nitrate anions are important?
needed in plants for the formation of amino acids/ proteins from the products of photosynthesis, and also the formation of DNA
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Why are phosphate anions important?
needed in al living organisms in the formation of ATP and ADP as well as DNA and RNA
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Why are chloride anions important?
needed in nerve impulses, sweating and many secretory systems
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Why are hydrogen carbonate anions important?
needed for buffering the blood to prevent it from becoming too acidic
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Why are sodium cations important?
needed in nerve impulses, sweating and many secretory systems
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Why are calcium cations important?
needed for the formation of calcium pectate for the middle lamella between two cell walls in plants, and for bone formation and muscle contraction in animals
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Why are hydrogen cations important?
needed in cellular respiration and photosynthesis, and in numerous pumps and systems in organisms as well as pH balance
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Why are magnesium cations important?
needed for production of chlorophyll in plants
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Polar solvent
many ionic substances ,like sodium chloride, can dissolve in it,. Many covalent molecules are polar so can also dissolve in water and not other covalent subsantces like ethanol. Most chemical reactions within cells occur water (aqueous solutions)
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Transport medium
water is an excellent transport medium as many different substances will dissolve in it
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Maximum density at 4c
As water cools further than 4c, the molecules become more widely spread. This means ice is less dense than water and floats. ]], forming an insulatig layer and helping to prevent the water underneath from freezing. Organisms can stay when frozen
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Slow to absorb and release heat
Water has a high specific heat capacity. The hydrogen bonds take a lot of energy to to break this means the temperature of large bodies of water such as lakes do not change throughout the year, making good habitats for living organisms
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Incopmressablitly
Water is a liquid and so cant be compressed. This means it is an important factor in many hydraulic mechanisms in living organisms
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Water molecules are cohesive
the forces between molecules mean they stick together. This is important in the movement of water molecules from the roots to the leaves in plants
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Water molecules are adhesive
They are attracted to other different molecules. This is also important in plant transport systems in surface tension
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Other cards in this set
Card 2
Front
Covalent bonding
Back
Sharing electrons. Form very strong bonds, usually neutral but occasionally slightly polarised. Electrons are not evenly shared, creates dipole (slighty negative and positive parts). Polar molecule - common if one or more hydrogen atoms are involved
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