Download presentation
Presentation is loading. Please wait.
Published byRosalind Jones Modified over 8 years ago
1
PERIODIC TABLE
2
Antoine Lavoisier (1790) Compiled list of known elements at that time (23)
3
John Newlands (1864) Organized elements based on atomic mass - Noticed a relationship of repeated properties every 8 elements. -called in the Law of Octaves
4
Dmitri Mendeleev (1869, Russian) Organized elements by increasing atomic mass. Elements with similar properties were grouped together. There were some discrepancies.
5
Dmitri Mendeleev Predicted properties of undiscovered elements. Became known as “Father of the Periodic table”
6
Henry Mosely (1913) Organized elements by increasing atomic number. Resolved discrepancies in Mendeleev’s arrangement. +There is a periodic repetition of chemical and physical properties of the elements when they are arranged by atomic number Periodic Law
8
All alkali metals have 1 valence electron Alkali metals are NEVER found pure in nature; they are too reactive Reactivity of these elements increases down the group Potassium, K reacts with water and must be stored in kerosene
9
All alkaline earth metals have 2 valence electrons Alkaline earth metals are less reactive than alkali metals Alkaline earth metals are not found pure in nature; they are too reactive The word “alkaline” means “basic” common bases include salts of the metals Ca(OH) 2 Mg(OH) 2
10
Metals are good conductors of heat and electricity Metals are malleable Metals are ductile Metals have high tensile strength Metals have luster
11
Copper, Cu, is a relatively soft metal, and a very good electrical conductor. Mercury, Hg, is the only metal that exists as a liquid at room temperature
12
Rare Earth metals Uses include industrial lasers, magnets and welding. Some also are used for coloring in ceramics and glass production.
13
They have properties of both metals and nonmetals. Metalloids are more brittle than metals, less brittle than most nonmetallic solids Metalloids are semiconductors of electricity Some metalloids possess metallic luster
14
Nonmetals are poor conductors of heat and electricity Nonmetals tend to be brittle Many nonmetals are gases at room temperature Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.
15
Sulfur, S, was once known as “brimstone” Microspheres of phosphorus, P, a reactive nonmetal Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure
16
Halogens all have 7 valence electrons Halogens are never found pure in nature; they are too reactive Halogens in their pure form are diatomic molecules (F 2, Cl 2, Br 2, and I 2 ) Chlorine is a yellow-green poisonous gas
17
Noble gases have 8 valence electrons (except helium, which has only 2) Noble gases are ONLY found pure in nature – they are chemically unreactive Colorless, odorless and unreactive; they were among the last of the natural elements to be discovered
19
Radius decreases across a period Increased effective nuclear charge due to decreased shielding Radius increases down a group Each row on the periodic table adds a “shell” or energy level to the atom Radius decreases across a period Increased effective nuclear charge due to decreased shielding Radius increases down a group Each row on the periodic table adds a “shell” or energy level to the atom
22
Based on trends answer the following: Place the following in order of largest to smallest atomic radius: Ca, Fe, Mo, Sn, Ra RaMoSnCaFe
23
Definition: the energy required to remove an electron from an atom Tends to increase across a period As radius decreases across a period, the electron you are removing is closer to the nucleus and harder to remove Tends to decrease down a group Outer electrons are farther from the nucleus and easier to remove Tends to increase across a period As radius decreases across a period, the electron you are removing is closer to the nucleus and harder to remove Tends to decrease down a group Outer electrons are farther from the nucleus and easier to remove
25
Successive Ionization Energies -Large jump in I.E. occurs when a CORE e - is removed. Al 1st I.E.577 kJ 2nd I.E.1,815 kJ 3rd I.E.2,740 kJ Core e - 4th I.E.11,600 kJ
26
Based on trends answer the following: Which of the following has a higher 1 st IE? Cs, Nb, or Pt ? Nb As, N, Be, or Ca ?Ca
27
ELECTRONEGATIVITY Definition: A measure of the ability of an atom in a chemical compound to attract electrons o Electronegativity tends to increase across a period o As radius decreases, electrons get closer to the bonding atom’s nucleus o Electronegativity tends to decrease down a group or remain the same o As radius increases, electrons are farther from the bonding atom’s nucleus o Electronegativity tends to increase across a period o As radius decreases, electrons get closer to the bonding atom’s nucleus o Electronegativity tends to decrease down a group or remain the same o As radius increases, electrons are farther from the bonding atom’s nucleus
28
Noble Gases do not have EN scores – Why?
30
IONIC RADII Cations Anions Positively charged ions formed when an atom of a metal loses one or more electrons Smaller than the corresponding atom Negatively charged ions formed when nonmetallic atoms gain one or more electrons Larger than the corresponding atom
31
Graphic courtesy Wikimedia Commons user Popnose
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.