Periodicity & the Periodic Table

The Atom in 1869 – Dmitri Mendeleev The First “Modern” Periodic Table

The Atom in 1869 – Dmitri Mendeleev Mendeleev’s “Periodic” Atomic Theory Elements of similar atomic mass display similar properties Elements with atomic masses that increase in equal increments display similar properties The elements can be arranged 2-dimensionally by their properties to predict “missing” elements. Think you’re as smart as Mendeleev?

Think you’re as smart as Mendeleev? Periodicity I’m a genius! Elements display repeating patterns based on their properties when arranged into a 2-dimensional grid Think you’re as smart as Mendeleev?

The basic idea: arrange cards so that patterns and trends follow logical orders across and up/down your table. Find missing boxes by finding "gaps" in the trends. Predict what's missing. B1 B2 A2 C1 C2 B3 D1 D2 A1 D3 A3

The basic idea: arrange cards so that patterns and trends follow logical orders across and up/down your table. Find missing boxes by finding "gaps" in the trends. Predict what's missing. A1 B1 C1 D1 A2 B2 C2 D2 A3 B3 D3

The basic idea: arrange cards so that patterns and trends follow logical orders across and up/down your table. Find missing boxes by finding "gaps" in the trends. Predict what's missing. A1 B1 C1 D1 A2 B2 C2 D2 B3 C3 A3 D3

Alien Periodic Table Arrange the cards you have been given into a grid- It will be a rectangle Aliens that demonstrate similar properties are adjacent- either side to side or under and over.

The Modern Periodic Table

The Modern Periodic Table What it REALLY looks like!

GROUPS Remember periodicity? How do Groups relate to periodicity? Group Numbers Remember periodicity? How do Groups relate to periodicity? NO Group Numbers (Names Only)

PERIODS Period Numbers And how does periodicity relate to periods?

6.2 Classification of the Elements Elements can be classified into four categories based upon their electron configurations Noble gases He, Ne, Ar, Kr, Xe, and Rn Full outer s and p sublevels Representative elements Groups 1A – 8A (this includes Noble Gases) Partially filled s and p sublevels

6.2 Classification of the Elements Transition metals d block Outer s and nearby d sublevel contain electrons Inner transition metals f block Outer s and nearby f sublevel contain electrons

Representative Elements Inner Transition Metals     Noble Gases Transition Metals Representative Elements Inner Transition Metals

GENERAL CATEGORIES Yeah. You gotta know ‘em.

General Properties Usually, metals are: Conductive Shiny Malleable Ductile Solid at room temperature (can you think of an exception?) The Alkali Metals are particularly interesting: Very soft, cut with a knife Highly reactive with air and water

Usually, non-metals are: Insulators Dull Brittle General Properties Usually, non-metals are: Insulators Dull Brittle Often gaseous at room temperature The Noble Gasses are particularly interesting: Exceptionally Nonreactive The Halogens are also very interesting: Tend to form diatomic molecules Highly reactive with almost everything

General Properties Metalloids: Some are like metals Some are like non-metals Properties vary greatly within a group

FAMILIES Yeah. You gotta know ‘em.

What is similar for all elements in a group or family?   These have 1 These have 3   They have the same number of outer level electrons!!!

Classification of the Elements Electrons, particularly the valence electrons, control many of the chemical and physical properties of atoms!

ALL TRENDS ARE EXPLAINED BY NUCLEAR CHARGE AND SHELLS AND SHIELDING 6.3 Periodic Trends Because the arrangement of elements on the periodic table is closely linked to the electron configuration, there are a number of trends that can be used to predict chemical and physical behavior. In order to understand and use these trends, you must first understand how NUCLEAR CHARGE and SHELLS AND SHIELDING influence electron behavior. ALL TRENDS ARE EXPLAINED BY NUCLEAR CHARGE AND SHELLS AND SHIELDING

6.3 Periodic Trends Nuclear Charge As you move across a period or down a group, the atomic number increases. This means the number of protons in the nucleus is increasing. With more protons, the positive pulling strength (nuclear charge) of the nucleus is increasing

Nuclear Strength Increases Increases  

6.3 Periodic Trends Shells Shielding Energy levels The higher the level, the farther from the nucleus Across – highest energy does not change Down – energy levels increase Shielding Inner level electrons interfere or shield the valence electrons from the nucleus Across – shielding is constant Down – shielding increases

Shells and Shielding Constant Increases  

Nuclear Charge verses Shells and Shielding Period Trend Nuclear Strength Wins!!! Because Shells and Shielding are constant across a period they don’t affect period trends Therefore, ALL PERIOD TRENDS are caused by increasing nuclear charge.

Nuclear Charge verses Shells and Shielding Group Trend Shells and Shielding Win Even though nuclear charge is increasing, more Shells (your farther from the nucleus) and Shielding (inner level electron interference) decreases the effective nuclear strength. Therefore, ALL GROUP TRENDS are caused by shells and shielding or their effect on the nuclear charge.

Nuclear Charge verses Shells and Shielding S/S Increases lowering effective Nuclear Strength Nuclear Strength Increases  

Atomic Radius Atomic radius – estimated as ½ the distance between the nuclei of 2 like atoms in a diatomic molecule. As atomic radius increases, the element increases in size.

Atomic Size

Atomic Size Size Increases Size Decreases  

Ion Formation Metals will lose electrons Nonmetals gain electrons Octet Rule – atoms will gain or lose electrons (sometimes even sharing like in molecules) to acquire a full set of 8 valence electrons. Metals will lose electrons Nonmetals gain electrons

Two hydrogen atoms are walking down the street. Hey, I think I just lost an electron! Are you sure! Yeah! I’m POSITIVE!

The Cation is smaller than the neutral atom! Ion Formation Cation – formed when electrons are removed from a neutral atom Nucleus has a stronger pull on the remaining electrons decreasing the size The Cation is smaller than the neutral atom!

The Anion is larger than the neutral atom! Ion Formation Anion – formed when electrons are added to a neutral atom Nucleus has a weaker hold on the increased number of valence electrons and the ion size increases The Anion is larger than the neutral atom!

Ion Size Period Trend Group Trend Cations and Anions both decrease in size across a period Group Trend Cations and Anions both increase in size down a group

Ionic Size Cations decrease Anions decrease Both increase

Ionization Energy Na(g)  Na+(g) + e- Ionization energy – energy needed to remove an electron from an atom Na(g)  Na+(g) + e-

Ionization Energy To remove an electron you have to overcome the nucleus’ hold on the electron. 1st Ionization Energy – Energy needed to remove first electron. 2nd Ionization Energy – Energy needed to remove a second electron. This is always higher than the 1st ionization energy. When an electron is removed, the nucleus has a stronger hold on the remaining electrons. When you have a noble gas electron configuration it becomes very difficult to remove an electron.

Ionization Energy

Ionization Energy Group Trend Period Trend Decreases as you go down a group The farther the outer electrons are farther from the nucleus, the weaker the pull. The inner level electrons block the nucleus’ ability to attract the valence electrons. Period Trend Increase as you go across a period

Ionization Energy 1st Ionization Energy decreases 1st Ionization Energy increases  

Electronegativity Electronegativity – attraction of one atoms nucleus to another atoms electrons when they are chemically bonded Measure of how strong the oxygen nucleus attracts the hydrogen’s electron H H O Water Molecule

Electronegativity H 2.1 Li 1.0 Be 1.5 B 2.0 C 2.5 N 3.0 O 3.5 F 4.0 Na   Li 1.0 Be 1.5 B 2.0 C 2.5 N 3.0 O 3.5 F 4.0 Na 0.9 Mg 1.2 Al Si 1.8 P S Cl K 0.8 Ca Ga 1.6 Ge As Se 2.4 Br 2.8 Rb Sr In 1.7 Sn Sb 1.9 Te I Cs 0.7 Ba Tl Pb Bi

Electronegativity Period Trend Group Trend Increases across a period Greater hold on electrons Group Trend Decreases down a group Weaker hold on the electrons

Electronegativity Electronegativity increases Electronegativity decreases Electronegativity increases  

Designing A Periodic Table Activity Arrange the cards you’ve been given into a grid. Your grid may or may not be perfectly square. Atoms with similar properties are adjacent, either side to side or over and under. There may be “gaps” where an element should be to make the similarity of properties make sense. Put your blank card in the gap. When you’ve found the missing element, interpolate its properties from its neighbors