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Elements, Atoms, and Ions
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The Language of Chemistry
_________________________- pure substances that cannot be decomposed by ordinary means to other substances. Aluminum Bromine Sodium
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The Language of Chemistry
The elements, their names, and symbols are given on the _____________ How many elements are there?
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The Periodic Table Dmitri Mendeleev ( )
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The Atom An atom consists of a _____________________
(of protons and neutrons) _________________ in space about the nucleus. Electron cloud Nucleus
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Composition of molecules is given by a ______________________
A ______________ is the smallest unit of a compound that retains the chemical characteristics of the compound. Composition of molecules is given by a ______________________ H2O C8H10N4O2 - caffeine
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Copper atoms on silica surface.
An ___________ is the smallest particle of an element that has the chemical properties of the element. Copper atoms on silica surface. Distance across = 1.8 nanometer (1.8 x 10-9 m)
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_________________are composed of atoms and so can be decomposed to those atoms.
The red compound is composed of • nickel (Ni) (silver) • carbon (C) (black) • hydrogen (H) (white) • oxygen (O) (red) • nitrogen (N) (blue)
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Compounds __________________ __________________ __________________
properties differ from those of individual elements EX: table salt (NaCl)
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ATOMIC COMPOSITION ________________________ (p+)
+ electrical charge mass = x g relative mass = atomic mass units (amu) but we can round to 1 _________________________ (e-) negative electrical charge relative mass = amu but we can round to 0 _________________________ (no) no electrical charge mass = amu but we can round to 1
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IONS ______________________ are atoms or groups of atoms with a positive or negative charge. Taking away an electron from an atom gives a ______________________with a positive charge Adding an electron to an atom gives an _____________________ with a negative charge. To tell the difference between an atom and an ion, look to see if there is a charge in the superscript! Examples: Na+ Ca+2 I- O-2 Na Ca I O
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Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons
C would like to N would like to O would like to Gain 4 electrons Gain 3 electrons Gain 2 electrons
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IONIC BOND __________________________________________________________________
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Ionic Bonds: One Big Greedy Thief Dog!
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COVALENT BOND __________________________________________________________________
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Covalent Bond Between nonmetallic elements of similar electronegativity. _______________________________________________________ Stable non-ionizing particles, they are not conductors at any state Examples; O2, CO2, C2H6, H2O, SiC
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______________________________________________________
NONPOLAR COVALENT BONDS ______________________________________________________ H2 or Cl2
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2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons.
Oxygen Atom Oxygen Atom Oxygen Molecule (O2)
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______________________________________________________
POLAR COVALENT BONDS ______________________________________________________ H2O
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Polar Covalent Bonds: Unevenly matched, but willing to share.
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- water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.
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