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CH 18 Properties of Atoms and the Periodic Table.

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Presentation on theme: "CH 18 Properties of Atoms and the Periodic Table."— Presentation transcript:

1 CH 18 Properties of Atoms and the Periodic Table

2 Structure of the Atom Chemical symbol — shorthand way to write element’s name; 1 or 2 letters Chemical symbol — shorthand way to write element’s name; 1 or 2 letters 1 st letter ALWAYS capitalized and if there is a 2 nd it is lowercase 1 st letter ALWAYS capitalized and if there is a 2 nd it is lowercase Case sensitive: CO≠Co Case sensitive: CO≠Co Some use Latin names, Ag is silver—Argentum in Latin Some use Latin names, Ag is silver—Argentum in Latin System used worldwide System used worldwide

3 Atoms—basic building blocks of all matter Atoms—basic building blocks of all matter Composed of: Composed of: Protons—in nucleus; + Protons—in nucleus; + Neutrons—nucleus; neutral Neutrons—nucleus; neutral Electrons—around nucleus; - Electrons—around nucleus; - Nucleus—positively charged center of atom Nucleus—positively charged center of atom

4 QuarksQuarksQuarksQuarks Quarks—what protons and neutrons are made of;6 types Quarks—what protons and neutrons are made of;6 types Up, down, charm, strange, top & bottom Up, down, charm, strange, top & bottom 3 arranged one way=proton (p + ) 3 arranged one way=proton (p + ) 3 arranged another way=neutron (n°) 3 arranged another way=neutron (n°)

5 Electron models Atomic models have changed thru-out history Atomic models have changed thru-out history Models showing where e- is located also changed (pg 548) Models showing where e- is located also changed (pg 548) Bohr’s model is the one we recognize Bohr’s model is the one we recognize

6 Electron models Electron cloud is current model Electron cloud is current model Cloud is the probable region where you would find an e- Cloud is the probable region where you would find an e- Cloud 100,000 times larger than nucleus! But e- is MUCH smaller than a p + Cloud 100,000 times larger than nucleus! But e- is MUCH smaller than a p +

7 Masses of Atoms Sec 2 Neutral atom— equal # of p+ and e- Neutral atom— equal # of p+ and e- Atomic mass unit (amu) used to measure atomic particles Atomic mass unit (amu) used to measure atomic particles Equal to 1/12th the mass of a carbon atom Equal to 1/12th the mass of a carbon atom

8 Masses of Atoms Sec 2 cont. Atomic # = # of p + Atomic # = # of p + Atomic mass=# of p + and n° (# above chem. symbol on your chart—larger #) Atomic mass=# of p + and n° (# above chem. symbol on your chart—larger #) Atomic mass – atomic # = # of n° Atomic mass – atomic # = # of n° Isotopes—atoms of the same element that have a different # of n° Isotopes—atoms of the same element that have a different # of n°

9 Sec 3 Periodic Table

10 Dmitri Mendleleev—Russian chemist (late 1800’s) arranged elements in order of increasing atomic mass Dmitri Mendleleev—Russian chemist (late 1800’s) arranged elements in order of increasing atomic mass Left blank spaces due to undiscovered elements Left blank spaces due to undiscovered elements Vertical columns (18) called groups/families Vertical columns (18) called groups/families # of outer e- are the same in each group # of outer e- are the same in each group Chemical properties are the same for the elements in each group Chemical properties are the same for the elements in each group Horizontal rows called periods Horizontal rows called periods

11 Metals—all elements left of the stair step Metals—all elements left of the stair step Properties: solids at room temp (except ?), Properties: solids at room temp (except ?), shiny, good conductors of heat and electricity Metalloids—elements near the stair step Metalloids—elements near the stair step Have properties of both metals and non-metals Have properties of both metals and non-metals Non-metals—right of stair step Non-metals—right of stair step Properties: most are gases, some brittle solids, poor conductors of heat/electricity Properties: most are gases, some brittle solids, poor conductors of heat/electricity Groups 3  12 called Transition elements: metals, but have properties not found in elements of other groups Groups 3  12 called Transition elements: metals, but have properties not found in elements of other groups

12 Energy levels of e- Energy levels of e- 1 st level, closest to the nucleus, lowest E, only holds 2 e- 1 st level, closest to the nucleus, lowest E, only holds 2 e- 2 nd level holds 8 e- 2 nd level holds 8 e- 3 rd level holds 18 e- 3 rd level holds 18 e- 4 th level holds 32 4 th level holds 32 e- e-

13 e- dot diagrams—represents the outermost e- of an element e- dot diagrams—represents the outermost e- of an element Called Lewis structures Called Lewis structures Chemical symbol and the # of e- in the outer level placed around the chem symbol using dots Chemical symbol and the # of e- in the outer level placed around the chem symbol using dots


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