periodic table chapter 6. periodic table many different versions of the periodic table exist all try...
TRANSCRIPT
Periodic Table
Chapter 6
Periodic Table
Many different versions of the Periodic Table exist
All try to arrange the known elements into an organized table
Alternate Periodic Tables
Alternate Periodic Tables
Alternate Periodic Tables
Alternate Periodic Tables
Alternate Periodic Tables
Alternate Periodic Tables
Alternate Periodic Tables
Elements known since Ancient times
Elements Discovered in 1600’s
Elements Discovered in 1700’s
Elements Discovered 1800-1810
Elements Discovered 1810-1863
Elements Discovered 1875-1899
Elements Discovered 1900-1940
Elements Discovered 1944-1961
Elements Discovered 1966-1996
Elements Discovered since1999
History
1869 - Russian chemist and teacher, Dmitri Mendeleev proposed a table for organizing elements
Mendeleev arranged the elements in a table based on increasing atomic mass.
History
Mendeleev placed elements next to each other with similar chemical properties
He would leave elements out of order based on atomic mass if they lined up better based on chemical properties
History
Mendeleev left spaces for elements not yet discovered– He predicted properties of elements that would fit
in those spots
He predicted very closely the properties of Ge, Ga, Sc, and 5 others
History
1913 - British physicist, Henry Moseley, determined the atomic numbers for the elements
The modern periodic table is arranged in order of increasing atomic number.
Periodic Table
Arrangement
Columns are called Groups– Numbered 1-18
Rows are called Periods
Elements in the same group have similar properties
Group Names
Group 1 - Alkali Metals
Group 2 - Alkaline earth metals
Group 17 - Halogens
Group 18 - Inert or Noble gases.
Group Names
Groups 3-11 – Transition Metals
Bottom 2 rows – Inner Transition
Phases at STP
Most elements are solids at STP
Hg and Br are liquids at STP
H, N, O, F, Cl and Noble Gases are all gases at STP
Periodic Law
Periodic Law – When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.
Valence Electrons
Electrons in outermost occupied energy level
Valence Electrons are responsible for most chemical properties– Elements in the same group have similar
properties because they have the same number of valence electrons
Classifying Elements
Elements are classified into 3 groups based on their properties:
Metals – Left and Middle
Nonmetals – Right
Metalloids - Staircase
Metals
Good conductors of heat and electrical current
High luster or sheen Many are ductile, meaning they can be
drawn into wires Most are malleable, meaning they can be
hammered into thin sheets
Metals
Metallic Character increases as you move towards the lower left
Most Metallic Element is Francium, Fr
Nonmetals
Most are gases at room temperature, some are solids, and one is liquid
Most are poor conductors
Most solids are brittle
Nonmetals
Non-Metallic Character increases as you move towards upper right
Most nonmetallic element is Fluorine, F
Metalloids
B, Si, Ge, As, Sb, Te
Have properties of both metals and nonmetals, based on conditions
Exceptions:– Al and Po are metals– At is a nonmetal
Group Characteristics
Alkali Metals (Group 1)– H, Li, Na, K, Rb, Cs, Fr– All have 1 valence electron, tend to form +1 ions– Most reactive metals– Not found in nature by themselves, always
combined with someone else– Have properties of metals but are softer and less
dense
Group Characteristics (cont)
Alkaline Earth Metals (Group 2)– Be, Mg, Ca, Sr, Ba, Ra– All have 2 valence electrons, tend to form +2 ions– Harder and more dense than alkali metals, but
also have higher melting and boiling points– Highly reactive, but not as much as alkali metals– Not found by themselves in nature
Group Characteristics (cont)
Halogens (Group 17)– F, Cl, Br, I, At– All have 7 valence electrons, tend to form -1 ions– Strongly non-metallic– Most active nonmetals– Have low melting and boiling points– Combine readily with metals to form salts
Group Characteristics (cont)
Noble Gases (Group 18)– He, Ne, Ar, Kr, Xe, Rn– Colorless gases that are extremely non-reactive– Full valence shell, non-reactive– All are found in small amounts in our atmosphere
Group Characteristics (cont)
Transition Metals (Groups 3-11)– Most are excellent heat and electrical conductors– Most have high melting points and are hard,
except Hg– Less active than group 1 and 2 metals– Many combine with Oxygen to form oxides
(Chemical property)– Many have more than one oxidation number– Form compounds that are colorful
Reminder
STP Standard Temperature and Pressure
– 1 atm, 0°C
Reference Point for most measurements
Diatomics
Eight elements are diatomic molecules when alone in nature (exist as two atoms bonded together)
H2, N2, O2, F2, Cl2, Br2, I2, At2
Diatomics
Hydrogen and the Magic 7
Coloring
Color in the specific groups with your own color choices
Coloring
Color in the different classifications with your own color choices
Metals, Nonmetals, Metalloids
Orbital Blocks
s - block
p - block
d - block
f - block
Periodic Trends
How a property changes either across a period or down a group– Atomic Number– Atomic Mass– Atomic Radius– Ionic Radius– Ionization Energy– Electronegativity
Trends
Atomic number increases across a period.– Increasing number of protons
Atomic number increases down a group– Increasing number of protons
Trends
Atomic mass generally increases across a period.– Increasing protons, neutrons, and electrons.
Atomic mass increases down a group.– Increasing protons, neutrons, and electrons.
Radius
Atomic Radius – measure of the size of the atom– Half the distance between two nuclei
Ionic Radius – measure of the size of an ion
Trends
Atomic Radius decreases across a period– More protons to pull on the electrons
Atomic Radius increases down a group– Increasing electrons into more energy levels
(more shells)
Ions
Atom, or group of atoms, that has gained or lost electrons
Cation – positive ion Anion – negative ion
Ions
When an atom loses an electron, it becomes positively charged– The radius becomes smaller– Metals tend to lose electrons
Ions
When an atom gains an electron, it becomes negatively charged– The radius becomes larger– Nonmetals tend to gain electrons
Trends
Ionic Radius decreases for positive ions across a period– More protons to pull on the electrons
Ionic Radius decreases for negative ions across a period– More protons to pull on the electrons
Ionic Radius
+1 +2 +3 +4 -3 -2 -1
Trends
Ionic Radius increases down a group– Increasing electrons into more energy levels
(more shells)
Ionization Energy (IE)
Amount of energy required to remove an electron from an atom– Ca Ca+ + e- 590kJ/mol
First ionization energy is removing the first electron
Second Ionization energy is removing the second electron after having the first removed– Ca+ Ca2+ + e- 1145kJ/mol
IE Trends
Ionization energy tends to increase across a period– More protons are able to hold on tighter to
electrons
Ionization energy tends to decrease down a group– Electrons are farther away from the protons (more
shells)
Electronegativity (EN)
Ability of an atom to attract an electron from another atom when in a compound. – Noble gases are usually omitted since they don’t
form compounds– Fluorine, F, is the most electronegative element
with a value of 4.0– Francium, Fr, is the least electronegative element
with a value of 0.7
EN Trends
Electronegativity tends to increase across a period– More protons are able to attract electrons better
Electronegativity tends to decrease down a group– Electrons are farther away from the protons (more
shells)
Trends Summary
Property Period (LR) Group (TB)
Atomic Number
Atomic Mass
Atomic Radius
Ionic Radius
Ionization Energy
Electronegativity
Reactivity
Elements that are more reactive tend to either gain or lose electrons very easily
Elements that lose electrons easily have low IE and low EN– Lower left, Fr
Elements that gain electrons easily have high IE and high EN– Upper right, F