Periodic Table Notes Unit 3 – Notes. Periodic Table Nonmetals are on the right side of the...
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Transcript of Periodic Table Notes Unit 3 – Notes. Periodic Table Nonmetals are on the right side of the...
Periodic Table NotesUnit 3 – Notes
Periodic Table
Nonmetals are on the right side of the periodic table (with the exception of H).
Periodic Table
Metals are on the left side of the chart.
Periodic Table
Metalloids border the stair-step line (with the exception of Al, Po, and At).
Diatomic Molecules
These seven elements occur naturally as molecules containing two atoms.
Ions
• When atoms lose or gain electrons, they become ions.– Cations are positive and are formed by elements on the
left side of the periodic chart.
– Anions are negative and are formed by elements on the right side of the periodic chart.
Development of Periodic Table
• Elements in the same group generally have similar chemical properties.
• Physical properties are not necessarily similar, however.
Development of Periodic Table
Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped.
Metals versus Nonmetals
• Metals tend to form cations.• Nonmetals tend to form anions.
Metals
They tend to be lustrous, malleable, ductile, and good conductors of heat and electricity.
Nonmetals• These are dull, brittle
substances that are poor conductors of heat and electricity.
• They tend to gain electrons in reactions with metals to acquire a noble gas configuration.
Metalloids
• These have some characteristics of metals and some of nonmetals.
• For instance, silicon looks shiny, but is brittle and fairly poor conductor.
Periodic Trends
• In this chapter, we will rationalize observed trends in– Sizes of atoms and ions.– Ionization energy.– Electronegativity
What Is the Size of an Atom?
The bonding atomic radius is defined as one-half of the distance between covalently bonded nuclei.
Measured in nanometers
Nuclear Charge
• The positive charge of the protons
• For example sodium has a nuclear charge of +11
Sizes of AtomsBonding atomic radius tends to… …decrease from left to
right across a row
…increase from top to bottom of a column
Atomic Radius
Ionization Energy
• The ionization energy is the amount of energy required to remove an electron from the ground state of an atom.– The first ionization energy is that energy
required to remove first electron.– The second ionization energy is that energy
required to remove second electron, etc.– Measured in J or kJ
Ionization Energy• It requires more energy to remove each successive
electron.• When all valence electrons have been removed, the
ionization energy takes a quantum leap.
Trends in First Ionization Energies
• As one goes down a column, less energy is required to remove the first electron.– For atoms in the same
group, Zeff is essentially the same, but the valence electrons are farther from the nucleus.
Electronegativity
• A measure of how well you attract electrons.– A scale of 0 – 4– Created by Linus Pauling