Bell Ringer Riddles 1 The man who invented

Bell Ringer - Riddles 1. The man who invented it doesn't want it. The man 2. 3. 4. 5. who bought it doesn't need it. The man who needs it doesn't know it. What is it? I run over fields and woods all day. Under the bed at night I sit not alone. My tongue hangs out, up and to the rear, awaiting to be filled in the morning. What am I? Throw it off the highest building, and I'll not break. But put me in the ocean, and I will. What am I? What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps? No sooner spoken than broken. What is it?

Answers to Riddles 1. A coffin 3. A tissue or a wave 2. A shoe

Answers to Riddles cont. 4. A river 5. Silence or a secret

The Periodic Table Chapter 5 p. 133 -164 History Structure Trends

Section I: Attempts at Classification

Dobereiner - 1817 Discovered groups of three elements with similar properties “Triads” n n n Ca – 40 amu Sr – 87. 6 amu Ba – 137 amu Mass of Sr is about ½ way between Ca and Ba

Newlands - 1863 Arranged elements in order of increasing atomic mass Found a repetition of similar properties with every 8 th element “Law of octaves” 7 column table with 7 rows

Mendeleev - 1870 Arranged elements in order of atomic mass with 8 long columns and several short columns Arrangement reflected properties of the elements Predicted existence of several elements to fill gaps in his table n These elements were later discovered and had the properties predicted

Mendeleev’s Periodic Law Properties of the elements are a periodic function of their atomic masses.

Moseley - 1913 Performed experiments to determine an accurate mass for several elements which seemed out of place on the table Noticed a pattern in the number of protons Reorganized elements in order of atomic number rather than mass

Modern Periodic Law: The physical and chemical properties of elements are periodic functions of their atomic numbers.

Modern Periodic Table Most significant addition to Mendeleev’s periodic table came with the discovery of the noble gases. A new row was added to the periodic table after their discovery.

Section II: The Modern Periodic Table

Periods 7 rows Can be determined from the element’s electron configuration (ec) Example: arsenic has an ec= [AR] 3 d 104 s 24 p 3 the 4 in 4 p 3 means that arsenic is in the fourth period 1 2 3 4 5 6 7

Periods Period number 1 2 3 4 5 6 7 Number of elements in period 2 8 8 18 18 32 32 Sublevels in order of filling 1 s 2 s 2 p 3 s 3 p 4 s 3 d 4 p 5 s 4 d 5 p 6 s 4 f 5 d 6 p 7 s 5 f 6 d, etc.

Groups or Families 18 columns

Groups or Families The group number is the same as the number of electrons in the outermost energy level of an atom. Except groups 10 though 18. The number of electrons in the outermost energy level of the atom is the group number -10. Example: Group 18 is the noble gases 18 – 10 = 8 We already knew that noble gases have 8 electrons in their outermost energy level.

This Arrangement Reflects: Properties Increasing atomic number Electron configuration

Electron Configuration: Li – 1 s 22 s 1 Na – 1 s 22 p 63 s 1 K – 1 s 22 p 63 s 23 p 64 s 1 All have 1 e- in the outer level All are similar in color and hardness All react vigorously with water All belong to family/group 1 Li Na K Same Family or Group

Electron Configuration: C - 1 s 22 p 2 C N O N - 1 s 22 p 3 O- 1 s 22 p 4 Same period All have a full 1 st energy level with e- in s and p orbitals of the second level Number of e- is increasing by 1 All are in period 2

Blocks: Based on the electron configurations of the elements, the periodic table can be divided into four blocks, the s, p, d, and f blocks. Block Elements s p d f Groups 1&2 13 – 18 3 – 12 Lanthanides & Actinides

Blocks: d s f p

Classification of Elements: Most of the elements are metals. Located on the left side of the table.

General Properties of Metals: 1 to 3 e- in outer energy level of most Lose e- to form bonds (+ ions) Shiny Hard Good conductors of heat Good conductors of electricity

Classification of Elements Cont. : Some elements are nonmetals and are found on the right side of the table.

General Properties of Nonmetals: 5 to 8 electrons in the outer level Gain e- to form bond (- ions) Brittle solids or gases Poor conductors of heat Poor conductors of electricity

Classification of Elements: Some elements have properties similar to both metals and nonmetals. These are found bordering the stair-step dividing line. n Exception: Al is a metal These elements are called metalloids.

metals metalloids nonmetals

Some of the Families/Groups Have Special Names. 1 – alkali metals 2 – alkaline earth metals 3 -12 – transition metals 16 – chalcogens 17 – halogens 18 – noble gases Elements 58 – 71 – lanthanides Elements 90 – 103 – actinides Lanthanides and actinides – rare earth metals

Think about trends!!! Trend- to show a tendency *Mirriam-Webster Online dictionary I want you to write down every thing that comes to your mind when you hear the word trend.

Trends Since trends are a tendency, they can be used to classify. In Chemistry, trends are used to arrange elements in the periodic table.

Part III: Trends on the Periodic Table

Atomic Radius One-half the distance between the nuclei of identical atoms that are bonded together. Radius depends on: n n the number of energy levels the strength of the nucleus

Each group represents a higher principal quantum number (n) As n increases, size of the e- cloud increases. F Cl Br Atomic radius increases down a family.

Across a period, nuclear charge increases by 1 for each element. A stronger nucleus acts like a stronger magnet which attracts the e- cloud. C N O Atomic radius decreases across a period.

Determine which is larger? Na or Rb? Rb Ag or Au? Au Cl or I? I Ni or Cu? Ni Al or Si? Al La or U? La K or Ca? K H or He? H

Ionic Radius Size of an ion Ions are charged atoms formed when: n Atoms lose ew (+ Ion) w Cation n Atoms gain ew (- Ion) w Anion

Cations- smaller than their respective neutral atoms. Remember that cations are the + charged ions. Metals usually lose all valence electrons. - e- + The nucleus pulls tighter on the remaining electrons. + more p+ than e- +

Anions are larger than their respective neutral atoms. Remember that anions are the - charged ions. Nonmetals usually gain electrons to complete the valence shell. + e- - Electrons repel each other and spread out more e- than p+ -

Which is larger? Ca or Ca+2 n Ca F or n F– 1 K or K+1 n K F-, Ne or Na+ F- O or O-2 n O-2

First Ionization Energy required to remove one electron from a neutral atom of an element. To avoid the influence of nearby atoms, measurements of ionization energies are made on isolated atoms in the gas phase. Factors that affect ionization energy: 1) Radius 2) Nuclear charge 3) Shielding effect 4) Stability of sublevels

1) Radius: The greater the distance between the nucleus and the valence electrons, the easier it is to lose an electron.

2) Nuclear charge: Within a period, the higher the nuclear charge, the higher the ionization energy.

3) Shielding Effect: Other e- block the pull of the nucleus on the outer e-. Electrons repel each other.

4) Stability of Sublevels: e- in filled or half-filled sublevels are extremely hard to remove. n Higher ionization energy than their immediate neighbors C N Highest IE O

General Trend for IE: Ionization energy increases as you go up a family and across a period.

As the atomic number increases, both the period and the group trends become less obvious

Electron Affinity: The attraction of an atom for an additional electron or the energy involved when an atom gains an electron to form an anion Factors affecting EA: 1) Size 2) Nuclear charge 3) Shielding effect 4) Stability of sublevels

1) Size: In large atoms, the nucleus exerts less pull on the outer level.

2) Nuclear charge: Within a period, an increase in nuclear charge creates a greater attractive force.

3) Shielding effect: High numbers of electrons repel additional electrons

4) Stability of sublevels: Filled or half-filled sublevels are more stable. n Don’t need any more electrons

General Trend for EA: EA increases as you go up a family and across a period. Electron affinity

Oxidation Numbers: Position in the periodic table can be used to predict oxidation numbers.

Elements with sx ec ending Elements with e- configurations ending with sx: n Lose x e- to form cations

Elements with dx ec ending Elements with e- configurations ending with dx: Lose s e- first n Lose d e- one at a time n w If more than 5 d e-, will lose only those in excess of 5 w If 10 d e-, will lose only s e-

Elements with px ec ending Elements with e- configurations ending with px: Gain e- to complete p and form anions n Lose p electrons first, then the s electrons to form cations n

Examples: V Ca – 4 s 2 +2 V – 4 s 23 d 3 + 2, + 3, + 4 and + 5 Fe – 4 s 23 d 6 +2 and +3 O – 2 s 22 p 4 - 2, +6 and +4