Chemistry Comes Alive

Chemistry Comes Alive - but different mass numbers...

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Chemistry Comes Alive Basic Chemistry: Matter: anything that has mass & takes up space - matter is composed of elements - states of matter: solid , liquid or gas Elements are composed of atoms Atoms are composed of subatomic particles : - protons (+ charge) - neutrons (no charge) - electrons (- charge) The atomic number of an atom = the number of protons in its nucleus - the periodic table is grouped according to atomic number (Hydrogen (H) has an atomic number of 1, Helium (He) has an atomic number of 2…) The atomic mass (mass number) of an atom is the number of protons + the number of neutrons in its nucleus - the mass of electrons is negligible - Hydrogen (H) has a mass number of 1 (no neutrons), Helium (He) has a mass number of 4… The atomic weight of an element is the average of the relative weights of all the isotopes of that element (the atomic weight of Hydrogen is 1.008). Isotopes are atoms of an element that have the same number of protons (atomic number)
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Unformatted text preview: but different mass numbers (different numbers of neutrons).- Examples : 12 C, 13 C, 14 C- Radioisotopes are unstable isotopes that spontaneously decay into more stable forms (it can take up to thousands of years for half the atoms in an element to decay to the stable state)- Radioactivity can be detected with scanning devices, & radioisotopes can be incorporated into biological moleculesthis makes radioisotopes useful tools for biological research & medicine). Carbon (C), Oxygen (O), Hydrogen (H) & Nitrogen (N) make up > 96% of the mass of a person- other elements in the human body: Calcium (Ca), Phosphorus (P), Potassium (K), Sulfur (S), Sodium (Na), Chlorine (Cl), Magnesium (Mg), Iron (Fe), Iodine (I) Molecules : 2 or more atoms held together by chemical bonds- when 2 or more atoms of the same element bind, they form a molecule of that element- when 2 or more different atoms bind, they form one molecule of a compound...
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Chemistry Comes Alive - but different mass numbers...

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