the periodic table
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The Periodic Table. Organizing the Elements. late 1790’s Antoine Lavoisier made a list of known elements contained 23 elements 1864 John Newlands looked further into organization The Law of Octaves – repeating trends every 8 elements. Dmitri Mendeleev. Late 1800’s Russia - PowerPoint PPT PresentationTRANSCRIPT
The Periodic Table
late 1790’s Antoine Lavoisier made a list of known elements◦ contained 23 elements
1864 John Newlands looked further into organization◦ The Law of Octaves –
repeating trends every 8 elements
Organizing the Elements
Late 1800’s Russia Grouped elements with similar properties
into columns◦ 7 columns were formed
Noble Gases (8th Column) were later discovered Was able to predict properties of missing
elements When Germanium was discovered, it fit his
predictions
Dmitri Mendeleev
Does mass always increase throughout the periodic table?◦ NOPE
Tellurium (52) Iodine (53) Nickel (28) Argon (18) Potassium (19)
Question
The properties of the elements are a periodic function of their atomic masses◦ periodic means repeating, like the moon cycle,
every month it repeats
**atomic number was not known during Mendeleev’s time
Mendeleev’s Periodic Law
The properties of the elements are a periodic function of their atomic numbers
Using x-rays, Henry Moseley determined the number of protons per element◦ This is Atomic Number
Elements with similar e- configurations are in the same columns known as “groups” or “families”◦ Families familiar characteristics◦ Families have the same number of v.e.’s
Today’s Periodic Law
Rows are periods, each row designates a different nrg level
Columns are groups or families and contain elements with similar properties
Notable rows and columns◦ Rows:
4f – Lanthanides 5f - Actinides
◦ Columns: 1 or IA – Alkali Metals 2 or IIA – Alkaline Earth Metals 17 or VIIA – Halogens 18 or VIIIA – Noble gases
The Modern Periodic Table
“A” Groups
Filling the ‘s’ and ‘p’ sublevels
Contains both metals and non metals
Representative Elements
“B” Groups
Fills the ‘d’ sublevels
Made up of only metals
Transition Metals
Fill the ‘f’ sublevels
Lanthanides Actinides
Inner Transition Metals
Luster (shine) Ductile (pulled into wires) Malleable (hammerable and won’t shatter) Good conductors of heat and electricity
Have 3 or less v.e.’s so they tend to lose them◦ Usually no more than 3 v.e.’s
Includes transition metals, actinides and lanthanides
Metals
Brittle (most are gaseous) Good insulators, not typically good
conductors of heat or electricity
Have 5 or more v.e.’s, so they tend to gain (or share) e-’s
Nonmetals
Elements with properties of both metals and nonmetals
Located on the diagonal between metals and nonmetals
There are 8 metalloids Can lose or gain v.e.’s depending on their
placement on the periodic table
Metalloids
8 e- in the outer nrg level make an atom not reactive or stable◦ Metals lose their e-’s to achieve octet
They become positive ( + ) = cations◦ Families 15 (VA), 16 (VIA), 17 (VIIA) gain e- to
achieve octet They become negative ( - ) = anions
All elements WANT 8 e-’s to become stable
Octet Rule
The most active metals are in the lower left corner of the periodic table
The most active nonmetals are in the upper right corner of the periodic table
Reactivity
Fr
F
Most active metal
Most active nonmetal
ReactivityDecreases
ReactivityDecreases
The Periodic TablePeriodic Trends
Increases as you go down a group◦ More e- = bigger radius◦ Atoms are gaining nrg levels
Decreases as you go across a period◦ e- are being added to the same nrg level◦ Nuclear charge – force of attraction between e-
and nucleus◦ As you move across a period, more e- are being
attracted to the nucleus
Atomic Radii
INCREASES as you go DOWN a group because of nrg levels
DECREASES as you go ACROSS a group because of nuclear charge
Noble gases radii are found to be larger because they don’t interact with other atoms of the same element as most others do.
Atomic Radii
Atomic Radii
Atoms can lose or gain e- to complete or empty an outer nrg level◦ Every atom wants an octet
Ion – an atom that has a + or – charge Metals
◦ Lose e- giving them a + charge◦ Decreases their radius◦ These are cations
Nonmetals◦ Gain e- giving them a – charge◦ Increases their radius◦ These are anions
Ions
Cations◦ H+, Li+, Na+, Mg2+, Ca2+
Anions◦ F-, Cl-, O2-, S2-, N3-, P3-
**noble gases don’t have ions, they are stable and DO NOT IONIZE
*carbon doesn’t ionize a lot, it “shares”◦ When it does ionize, it gains 4 e-
Sizably increases its radius
Examples of Ions
Nrg needed to remove an e- from an atom◦ Unit = (kJ/mol)
ACROSS a period, it INCREASES◦ Due to increase in nuclear charge
DOWN a group, it DECREASES◦ Due to increased atomic radius and shielding effect
Metals = low I.E. Nonmetals = high I.E. (especially noble
gases)
Ionization Energy
Nrg needed to remove a second e- from an atom◦ Typically harder to remove a 2nd e-
**The higher the I.E., the more stable the atom.
2nd Ionization Energy
BeB
1s 2s 2p
1s 2s 2p
More stable, full/empty sublevels
Less stable, partial sublevels
The power of an atom in a molecule to ATTRACT e- to itself◦ Ability to “hold on to e- more”◦ DECREASES from top to bottom of group◦ INCREASES from left to right in periods◦ F has the highest E.N.
High E.N.’s gain e- and form (-) ions◦ The more stable an atom, the less likely it will
attract an e- Would result in (-)E.N.
High E.N. = High electron affinity
Electronegativity
Like tug-o-war◦ Big guy (high E.N.)◦ Little guy (low E.N.)
Electronegativity
FDecrease in E.N.
Decrease in E.N.
Most active metals (lower left) have the LOWEST E.N.
Fluorine has the highest E.N.
Noble Gases have NO E.N., because they don’t typically bond
No units for E.N. because it is a comparison
Deals with compounds and bonding
Facts