Compare and contrast the arrangement of elements in Mendeléev’s Periodic Table and the Modern Periodic Table.
Mendeleev’s periodic table |
Modern |
---|---|
1. Elements are arranged in the increasing order of their atomic masses. | 1. Elements are arranged in the increasing order of their atomic numbers. |
2. There are a total of 7 groups (columns) and 6 periods (rows). | 2. There are a total of 18 groups (columns) and 7 periods (rows). |
3. Elements having similar properties were placed directly under one another. | 3. Elements having the same valence shell are present in the same period while elements having the same number of valence electrons are present in the same group. |
4. The position of hydrogen could not be explained. | 4. Hydrogen is placed above alkali metals. |
5. No distinguishing positions for metals and non-metals. | 5. Metals are present at the left hand side of the periodic table whereas non-metals are present at the right hand side. |
(a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?
The position of three elements A, B and C in the Periodic Table are shown below –
Group 16 Group 17
- -
- A
- -
B C
(a) State whether A is a metal or non-metal.
(b) State whether C is more reactive or less reactive than A.
(c) Will C be larger or smaller in size than B?
(d) Which type of ion, cation or anion, will be formed by element A?
How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?
Which element has
(a) two shells, both of which are completely filled with electrons?
(b) the electronic configuration 2, 8, 2?
(c) a total of three shells, with four electrons in its valence shell?
(d) a total of two shells, with three electrons in its valence shell?
(e) twice as many electrons in its second shell as in its first shell?
How could the Modern Periodic Table remove various anomalies of Mendeléev’s Periodic Table?
Element X forms a chloride with the formula XCl2, which is a solid with a high melting point. X would most likely be in the same group of the Periodic Table as
(a) Na (b) Mg (c) AI (d) Si
Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.
In the Modern Periodic Table, which are the metals among the first ten elements?
Use Mendeléev’s Periodic Table to predict the formulae for the oxides of the following elements:
K, C, AI, Si, Ba.
Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?
What is a good source of energy?
Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
What changes can you make in your habits to become more environment-friendly?
What is the difference between a reflex action and walking?
What is the importance of DNA copying in reproduction?
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Why should a magnesium ribbon be cleared before burning in air?
Define the principal focus of a concave mirror.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Name two safety measures commonly used in electric circuits and appliances.
Asexual reproduction takes place through budding in
(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.
How does our body respond when adrenaline is secreted into the blood?
What are the functions performed by the testis in human beings?
How does chemical coordination take place in animals?
How will an organism be benefited if it reproduces through spores?
How does the embryo get nourishment inside the mother’s body?
What changes can you make in your habits to become more environment-friendly?
How do we detect the smell of an agarbatti (incense stick)?
What is the need for a system of control and coordination in an organism?