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Atom?
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The smallest stable units of matter, composed of subatomic particles - protons, neutrons and electrons
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Proton?
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P+ have a positive electrical charge
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Neutron?
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Electrically neutral
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Electron?
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E- lighter than protons, have a negative charge, occupy a circular electron shell
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The mass of an atom?
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Determined by the number of protons and neutrons in the nucleus, the center region of an atom
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Atomic number?
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The number of protos in an atom
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Electrical force?
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The attraction between opposite electrical charges
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Electron cloud?
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Electrons travelling around the nucleus at high speed, dimetions of the electron cloud determine the overall size of the atom
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Element?
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Pure substance composed of atoms of only one kind
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Important elements in the human body?
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oxygen - 65% - essential for respiration
Carbon - 18.9% - found in all organic molecules
Hydrogen - 9.7% - component of water
Calcium - 1.8% - bones, teeth, membrane functioning, nerve impulses, muscle contraction and blood clotting
Phosphorus - 1.0% - bones, teeth, nucleic acids and high-energy compounds
Potassium - 0.4% - membrane functioning, nerve impulses, muscle contraction
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Isotopes?
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Atoms of the same element whose neclei contain the same number of protons but different number of neutorns
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A high-energy bond in ATP is present?
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Between the first and second phosphate group and between second and third phosphate group.
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Atomic weight?
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Actual mass of an atom, unit used to express atomic weight is the dalton (amu).
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Valence cell?
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The outermost energy level of the atom, number of electrons in thes level determines the chemical propetries of the element,
atoms with unfilled energy levels are unstable, atoms with filled outermost energy level are stable and don't readily react with other atoms
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Inert?
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Elements that do not readily participate in chemical processes - with filled outermost energy levels
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