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Write these questions in your NB. Compare/Contrast an Element vs. Compound Who is attributed with developing the Periodic Table? How was the 1 st Periodic Table Arranged? How is that different from now? What is periodicity?. Periodic Patterns. Unit 4 – Periodic Table. METALLIC TREND.
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Write these questions in your NB • Compare/Contrast an Element vs. Compound • Who is attributed with developing the Periodic Table? • How was the 1st Periodic Table Arranged? How is that different from now? • What is periodicity?
Periodic Patterns Unit 4 – Periodic Table
METALLIC TREND INCREASES INCREASES
ATOMIC RADIUS • Radius is the distance from the center of the nucleus to the “edge” of the electron cloud. • Atomic radii are usually measured in picometers (pm) or angstroms (Å). An angstrom is 1 x 10-10m.
ATOMIC RADII TRENDS DOWN A FAMILY OR GROUP WHY? • As you go down a family thenvalue increases making the radius larger. INCREASES
ATOMIC RADII TRENDS ACROSS A PERIOD WHY? • As you go across a period the number of protons increases, (nuclear charge) pulling the electrons in tighter making the radius smaller. DECREASES
IONS- Has a charge Metals • Lose electrons becoming positive. Calcium – Ca Loses 2 e-s becoming Ca+2 Nonmetals • Gain electrons becoming negative. Chlorine – Cl Gains one e- becoming Cl-1
IONS – How can I remember? Metals Nonmetals This is Cat-ion - CATION This is Ann ion - ANION He is a “plussy” cat! She is unhappy and negative.
IONIC RADII TRENDS DOWN A FAMILY OR GROUP WHY? • As you go down a family thenvalue increases making the radius larger. INCREASES
IONIC RADII TRENDS ACROSS A PERIOD WHY? • For the metals thenuclear chargeis greater than then number of electronspulling them in tighter making the radius smaller. • At the nonmetals the radius gets larger because the ion has gained electrons. DECREASES then INCREASE
Shielding Effect As more electrons are added to atoms, the inner layers of electrons shield the outer electrons from the nucleus. The effective nuclear charge on those outer electrons is less, and so the outer electrons are less tightly held
Ionization Energy The energy required to remove an electron from an atom is ionization energy. (measured in kilojoules, kJ)
IONIZATION ENERGY The larger the atom is, the easier its electrons are to remove. Ionization energy and atomic radius are inversely proportional. Ionization energy is always endothermic, that is energy is added to the atom to remove the electron.
IONIZATION TREND INCREASES INCREASES
Electron Affinity is a measure of the energy change when an electron is added to a neutral atom to form a negative ion
ELECTRON AFFINITY Why do the Alkaline Earth Metals and Noble Gases not have measurable Electron Affinities?
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.
In Summary…. Electronegativity Electronegativity