Chemical Properties and Periodicity ALKALI METALS: Physically they are solid, soft, malleable, conductors and have low density (large atoms) and low melting points compared with other metals (only 1 e- contributes to the metallic bond). These last two properties decrease as we move down the group, because the size of the atom increases. Have 1 e- in the outer level Form 1+ ions The alkali metals are very reactive

Chemical Properties and Periodicity They react with oxygen or with halogens to form binary ionic compounds: Some reactions of alkali metals: 2Li 2 O(s) 2KCl(s) 2NaBr(s) 2NaOH(aq) + H 2 (g) 4Li (s) + O 2 (g) 2K(s) + Cl 2 (g) 2Na(s) + Br 2 (l) They react vigorously with water: Na(s) + 2H 2 O(l) They must be stored in kerosene because they react explosively with water from the atmosphere…

…Reactions of alkali metals 2MOH(aq) + H 2 (g)M(s) + 2H 2 O(l) This reaction is the same for all alkali metals but it becomes more vigorous as we move down the group (Slow with Li, vigorous with Na and violent with K). M+(aq) and OH-(aq) Very alkaline (basic) solution

Basic Information Name: Lithium Symbol: Li Atomic Number: 3 Atomic Mass: amu Melting Point: °C ( °K, °F) Boiling Point: °C ( °K, °F) Number of Protons/Electrons: 3 Number of Neutrons: 4 Classification: Alkali Metal Crystal Structure: Cubic 293 K: 0.53 g/cm 3 Color: silveryAlkali Metal Atomic Structure Isotopes Isotope Half Life Li-6Stable Li-7Stable Facts Date of Discovery: 1817 Discoverer: Johann Arfvedson Name Origin: From the Greek word lithos (stone) Uses: batteries, ceramics, lubricants Obtained From: passing electric charge through melted lithium chloride, spodumene Number of Energy Levels: 2 First Energy Level: 2 Second Energy Level: 1

Isotop e Half Life Li-6Stable Li-7Stable FACTS Date of Discovery: 1817 Discoverer: Johann Arfvedson Name Origin: From the Greek word lithos (stone) Uses: batteries, ceramics, lubricants Obtained From: passing electric charge through melted lithium chloride, spodumene ISOTOPES

Basic Information Name: Sodium Symbol: Na Atomic Number: 11 Atomic Mass: amu Melting Point: 97.8 °C ( °K, °F) Boiling Point: °C ( °K, °F) Number of Protons/Electrons: 11 Number of Neutrons: 12 Classification: Alkali Metal Crystal Structure: Cubic 293 K: g/cm 3 Color: silveryAlkali Metal Atomic Structure Number of Energy Levels: 3 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 1

Isotope Half Life Na years Na-23Stable Na hours Facts Date of Discovery: 1807 Discoverer: Sir Humphrey Davy Name Origin: soda (Na 2 CO 3 ) Symbol Origin: From the Latin word natrium (sodium) Uses: medicine, agriculture Obtained From: table salts and other foods Isotopes

Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 8 Fourth Energy Level: 1 Basic Information Name: Potassium Symbol: K Atomic Number: 19 Atomic Mass: amu Melting Point: °C (336.8 °K, °F) Boiling Point: °C ( °K, °F) Number of Protons/Electrons: 19 Number of Neutrons: 20 Classification: Alkali Metal Crystal Structure: Cubic 293 K: g/cm 3 Color: silveryAlkali Metal

Isotopes Isotope Half Life K-39Stable K E9 years K-41Stable K hours K hours Facts Date of Discovery: 1807 Discoverer: Sir Humphrey Davy Name Origin: potash Symbol Origin: From the Latin word kalium Uses: glass, soap Obtained From: minerals (carnallite)

If you want information about Rb, Cs and Fr use the following links Rb: Cs: Fr:

All the halogens exist in the form of diatomic molecules: F 2, Cl 2, Br 2, I 2, At 2 Physically the first two, F 2, Cl 2, are gases, Br 2 is liquid, I 2 is a solid that sublimates at room temperature. They show different colors, for example Chlorine is green, Iodine is black and Bromine is red-brown. They are slightly soluble in water (because they are non polar): X 2 + H 2 O  H + + X - + HOX In polar solvens (like H 2 O and ethanol) Iodine forms a brown solution, but in non-polar solvents it forms a purple solution. The Halogens

They have 7 e- in the outer level, so they need 1 e- to become isoelectronic with a noble gas.Therefore they form 1 - ions. They react with metals to form binary compounds: 2LiF(aq) 2KCl(aq) 2NaBr(aq) 2Li (s) + F 2 (g) 2K(s) + Cl 2 (g) 2Na(s) + Br 2 (l) Some reactions of halogens These halides are usually white and soluble in water The insoluble halides are the ones formed with silver like AgCl, AgBr and AgI : Ag + (aq) + X - (aq)  AgX(s). The halides of Lead (II) are insoluble but can be dissolved hot water. Lead (II) iodide (PbI 2 ) is yellow.

The previous reactions and properties can be used to test for the presence of halides as follows: First add nitric acid to prevent other substances like carbonates to form precipitates and confuse the results. Then add silver nitrate. NaCl(aq) + AgNO 3 (aq)  NaNO 3 (aq) + AgCl(s) The formation of a precipitate indicates the presence of chloride, iodide or bromide ions. (Fluorine doesn’t form a precipitate) AgCl(s) is white and darkens with sunlight AgBr(s) is white AgI(s) is pale yellow Cont…Some reactions of halogens

Other reactions of halogens The halogens can undergo SINGLE REPLACEMENT REACTIONS: X 2 + MY Y 2 + MX F 2 (g) + 2NaCl(aq) Cl 2 (g) + 2NaF(aq) Example:

A +BC  AC + B An element takes the place of another element in a compound. N.R. It could be a metal taking the place of another metal or hydrogen. Mg(s) + FeSO 4 (aq) MgSO 4 (aq) + Fe(s) Magnesium is more active than Iron Fe(s) + MgSO 4 (aq) Review of Single Replacement Reactions

It could be also a halogen taking the place of another halogen. 2 KCl(aq) + Br 2 (aq)Cl 2 (g) + 2KBr(aq) Chlorine is more active than Bromine! Br 2 (aq) + KCl(aq) N.R. …cont…Single Replacement

An atom or ion is oxidized when it loses electrons in a reaction An atom or ion is reduced when it gains electrons in a reaction Halogens tend to be reduced to form the negative ion (halide) An atom that tends to be reduced is an oxidizing agent, because it makes other elements to be oxidized. Halogens act as oxidizing agents in a single replacement reaction The oxidizing power decreases down a group because they have less tendency to be reduced (becoming negative). Oxidizing power

That is why a higher halogen in the PT can replace a lower halogen and form its salt. But a lower halogen in the PT cannot replace A higher halogen This could be also expressed in the following way: …Cont…Oxidizing power Cl 2 (g) + 2KI(aq) 2 KCl(aq) + I 2 (aq) KCl(aq) + I 2 (aq) NR Cl 2 (g) + 2I - (aq)2 Cl - (aq) + I 2 (aq) Cl 2 (g) + 2I - (aq)

Basic Information Name: Fluorine Symbol: F Atomic Number: 9 Atomic Mass: amu Melting Point: °C ( °K, °F) Boiling Point: °C (85.01 °K, °F) Number of Protons/Electrons: 9 Number of Neutrons: 10 Classification: Halogen Crystal Structure: Cubic 293 K: g/cm 3 Color: GreenishHalogen Number of Energy Levels: 2 First Energy Level: 2 Second Energy Level: 7

Isotopes Half Life F hours F-19Stable Facts Date of Discovery: 1886 Discoverer: Joseph Henri Moissan Name Origin: From the Latin word fluo (flow) Uses: Refrigerants Obtained From: mineral fluorite Isotope

Basic Information Name: Chlorine Symbol: Cl Atomic Number: 17 Atomic Mass: amu Melting Point: °C ( °K, °F) Boiling Point: °C ( °K, °F) Number of Protons/Electrons: 17 Number of Neutrons: 18 Classification: Halogen Crystal Structure: Orthorhombic 293 K: g/cm 3 Color: greenHalogen Number of Energy Levels: 3 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 7

Atomic Structure Isotope Half Life Cl-35Stable Cl years Cl-37Stable Cl minutes Facts Date of Discovery: 1774 Discoverer: Carl Wilhelm Scheele Name Origin: From the Greek word khlôros (green) Uses: Water purification, bleaches Obtained From: Salt

Atomic Mass: amu Melting Point: -7.2 °C ( °K, °F) Boiling Point: °C ( °K, °F) Number of Protons/Electrons: 35 Number of Neutrons: 45 Classification: Halogen Crystal Structure: Orthorhombic 293 K: g/cm 3 Color: RedHalogen Number of Energy Levels: 4 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 7 Name: Bromine Symbol: Br Atomic Number: 35

Facts Date of Discovery: 1826 Discoverer: Antoine J. Balard Name Origin: From the Greek word brômos (stench) Uses: Poisonous Obtained From: Sea Water Isotope Half Life Br hours Br days Br-79Stable Br minutes Br- 80m 4.42 hours Br-81Stable Br days Br hours Br minutes Br minutes

Number of Energy Levels: 5 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 18 Fifth Energy Level: 7 Basic Information Name: Iodine Symbol: I Atomic Number: 53 Atomic Mass: amu Melting Point: °C ( °K, °F) Boiling Point: °C ( °K, °F) Number of Protons/Electrons: 53 Number of Neutrons: 74 Classification: Halogen Crystal Structure: Orthorhombic 293 K: 4.93 g/cm 3 Color: blackishHalogen

Facts Date of Discovery: 1811 Discoverer: Bernard Courtois Name Origin: From the Greek word iôdes (violet) Uses: required in humans Obtained From: sodium and potassium compounds Isotopes Isotope/ Half Life I minutes I hours I days I days I days I Stable I minutes I E7 years Isotopes..cont… Isotope/ Half Life I hours I days I hours I hours I minutes I hours I minutes

Name: Astatine Symbol: At Atomic Number: 85 Atomic Mass: (210.0) amu Melting Point: °C ( °K, °F) Boiling Point: °C ( °K, °F) Number of Protons/Electrons: 85 Number of Neutrons: 125 Classification: Halogen Crystal Structure: Unknown 293 K: Unknown Color: UnknownHalogen Number of Energy Levels: 6 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 32 Fifth Energy Level: 18 Sixth Energy Level: 7

Isotopes Isotope Half Life At minutes At hours At hours At milliseconds At milliseconds At seconds At seconds Facts Date of Discovery: 1940 Discoverer: D.R. Corson Name Origin: From the Greek word astatos (unstable) Uses: No uses known Obtained From: Man-made

The metallic properties of the elements decrease from left to right in the PT. The elements at´ the left have low ionization energy so they form + ions that form ionic compounds with negative ions. The elements at the right form either ionic compounds with metals or covalent compounds with nonmetals. Trends across a period

The oxides of metals are ionic and if you dissolve them in water, they form basic solutions: Na 2 O(aq) + H 2 O(l)  2NaOH(aq) The oxides of non metals, towards the middle of thePT, are covalent and in water form acid solutions: SO 3 (g) + H 2 O(l)  H 2 SO 4 (aq) CO 2 (g) + H 2 O(l)  H 2 CO 3 (aq)  H + (aq) + HCO 3 - (aq) The chlorides of metals are ionic and dissolve in water to dissociate in the metal positve ion and the halogen negative ion (halide). The solutions are neutral: NaCl(aq) H 2 O(l)  Na + (aq) + Cl - (aq) Towards the middle of the table, the chlorides dissolve in water to give acidic solutions: SiCl 4 (aq) + 2 H 2 O(l)  SiO 2 + 4H + + 4Cl - Cont…Trends across a period