Chapter 3 PERIODIC TABLE AND PERIODICITY OF PROPERTIES Q.1 What are the contributions of Dobereiner‚ Newland‚ Luthar Meyer and Mendeleef in the present shape of long form periodic table ? Dobereiner’s Triads : In 1829‚ a German scientist‚ John Dobereiner classified specific elements into groups in order of increasing atomic masses. Each group has three elements. He named these groups as triads.He noticed that the atomic mass of the middle elements was found to be approximately equal to the
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Fe‚ Cu Zn iii) show multiple valencies? C iv) are hard? Fe‚ Cu Zn v) are highly reactive? Li‚ Na. K‚ F‚ Cl‚ Br 2. (a) Which of the two metals lithium or rubidium (i) is harder? Lithium (ii) has a higher density? Lithium (iii) has a lower melting point? Rubidium (b) How are these metals stored and what is the reason for it? They are stored in oil to prevent them from reacting with the moisture in the air and oxygen. 3. A 26.5g sample
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The mythology about rubies is vast and it varies. Some cultures associate it with the Zodiac sign of Capricorn (goat) and in other cultures‚ Taurus (bull). Most cultures consider the ruby as the birthstone for July. However‚ throughout the ages it has been associated with nearly every other month. Ruby’s Day is Tuesday‚ it’s season Summer‚ and it’s apostle St. Matthew. Rubies are a traditional gift for 40th wedding anniversaries. In myth and magic‚ at the time of the Borgias (15-16th century)‚
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5. Part of the lanthanide series: cerium or thorium? 6. Larger atoms: carbon or fluorine? 7. Very high ionization energy: krypton or potassium? 8. Configuration ending in s1: strontium or lithium? 9. A 1+ or 1- charge: hydrogen or rubidium? 10. Named after the theorizer of relativity: curium or einsteinium? 11. Configuration ends in 3p1: aluminum or sulfur? 12. Gives a yellow-green flame test: potassium or barium? 13. Named after an Eastern Hemisphere continent: americium
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Dating Dating techniques are procedures used by scientists to determine the age of a specimen. 2 types of Dating: *Relative Dating *Absolute Dating Relative Dating -methods tell only if one sample is older or younger than another sample. -They do not provide an age in years. Stratigraphy -Main Relative Dating Method -is the study of layers of rocks or the objects embedded within those layers. -based on the assumption that deeper layers were deposited earlier‚ and thus are older than
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Alkali Metals Introduction Alkali metals refer to six elements belonging to the Group IA of the long form of the Modern Periodic Table‚ viz. Lithium (Li)‚ Sodium (Na)‚ Potassium (K)‚ Rubidium (Rb)‚ Cesium (Cs) and Francium (Fr). Fr is a radioactive element. These elements are called so because they form strongly alkaline oxides and hydroxides. Electronic Configuration of Alkali Metals Each of the alkali metals has one electron in their outermost (valence) shell‚ which is just outside an inert
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You are probably wondering what this table of colourful boxes is? Well you’ve come to the right place‚ I hope. What is it? Well everything in the world is made up of elements‚ well almost everything‚ light‚ heat‚ this is energy‚ another story. And elements are a single type of atom‚ the periodic table is basically a table of all know elements to man. What’s in it? To understand what’s in it we need to look at an atom and it subatomic parts. An atom is made up of an Electron(e-) this has a negative
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HKCEE 1995 Q1 Rubidium (Rb) and potassium belong to the same group in the Periodic Table. The relative atomic mass of rubidium is larger then that of potassium. (a) Explain whether rubidium is more reactive than potassium. (b) Write a chemical equation for the reaction between rubidium and water. (State symbols should be given.) (c) Suggest how rubidium can be stored safely in the laboratory. (d) Suggest ONE safety precaution for handling rubidium in the laboratory.
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Lithium‚Sodium‚Potassium‚Rubidium‚Caesium and Francium are all part of group 1.They are metals that can be easily cut.After being cut‚it is shiny but it quickly tarnishes due to the fact that the metal reacts quickly with oxygen or water.The shiny surfaces of Sodium quickly tarnishes more quickly than Lithium and Potassium more tarnishes more quickly than Lithium.This shows that the reactivity increases as we move down the group. Figure 1 Elements Melting point Boiling point Thermal
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this Section.) 1. Rubidium (Rb) and potassium belong to the same group in the Periodic Table. The relative atomic mass of rubidium is larger than that of potassium. (a) Explain whether rubidium is more reactive than potassium. (b) Write a chemical equation for the reaction between rubidium and water. (State symbols should be given.) (c) Suggest how rubidium can be stored safely in the laboratory. (d) Suggest ONE safety precaution for handling rubidium in the laboratory. (5
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