The Context of Congressional Elections Jacobson, Chapters 1, 2, and 3.
Chapters 3 - 4 – The Chemical Context of Life. Matter: takes up space and has mass.
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Transcript of Chapters 3 - 4 – The Chemical Context of Life. Matter: takes up space and has mass.
Atomic structureAtom is the smallest unit of
matter (an element) that still retains properties of an element
Atomic structure
MoleculeSmallest particle of a substance composed of at least 2 atoms
water
oxygen
a sugar
Proton(Positive charge)
Neutron(No charge)
Electron(Negative charge)
Hydrogen1 Proton1 Electron
Oxygen8 Protons8 Neutrons8 Electrons
Atomic number = # of protons
Atoms with the same atomic number belong to the same element, and thus have the same inherent properties.
Atomic structure
Electron shell
• Electron shell is an energy level in which electrons reside
• 1st shell: maximum 2 electrons• 2nd shell: maximum 8 electrons• 3rd shell: maximum 8 electrons• 4th & 5th shells: 18 electrons• Atoms are most stable when outer shell is
filled
• Atoms tend to react in ways that allow them to fill their outer shell– Most elements found in living systems react to
gain 8 electrons in their outer shells
Octet rule
Third energy level (shell)
Second energy level (shell)
First energy level (shell)
Atomicnucleus
Energyabsorbed
Energylost
Electrons and energy
• Some atoms can form more than one bond.– Hydrogen: one bond– Oxygen: two bonds– Nitrogen: three bonds– Carbon: four bonds
Covalent Bonds
Na+
Sodium ion(a cation)
Cl–
Chlorine ion(an anion)
Ions+ -
Ion: A atom carrying a electric charge which is formed either by gaining or losing electrons.
Na
Sodium atom(an uncharged
atom)
Cl
Chlorine atom(an uncharged
atom)
Na+
Sodium ion(a cation)
Cl–
Chlorine ion(an anion)
Sodium chloride (NaCl)
Ionic bonding
–
+
OxygenHydrogen
Hydrogen
Bohr model
8+8n
+
+
–
+
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Hydrogen bonds