Compare and contrast the arrangement of elements
[question] Question. Compare and contrast the arrangement of elements in Mendeleev’s Periodic Table and the Modern Periodic Table. [/question] [solution] solution: [/solution]...
In the Modern Periodic Table,
[question] Question. In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21, and 38. Which of these have physical and chemical properties resembling calcium? [/question] [solution] solution: The elements with atomic number 12 and 38 have same chemical properties as that of calcium. This is because both of them have same number of valence electrons (2) as calcium. Since elements with same number of valence electron have similar properties...
How does the electronic configuration of an atom relate
[question] Question. How does the electronic configuration of an atom relate to its position in the Modern Periodic Table? [/question] [solution] solution: In the Modern Periodic Table, atoms with similar electronic configurations are placed in the same group. In a group, the number of valence electrons remains the same. Elements across a period show an increase in the number of valence electrons in the same shell. [/solution]...
Nitrogen (atomic number 7 ) and phosphorus (atomic number 15 ) belong to group
[question] Question. 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? Element K L M Nitrogen 2 5 Phosphorus 2 8 5 [/question] [solution] solution: Nitrogen is more electronegative than phosphorus. On moving down a group, the number of shell increases. Therefore, the valence electrons move away from the nucleus and the effective nuclea...
The position of three elements
[question] Question. The position of three elements A, B and C in the Periodic Table are shown below ? (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? [solution] solution: (a) A is a non-metal. (b) C is more reactive than A (c) C will be smaller in size than B (d) A will form an anion [/solution]...
An atom has electronic configuration 2, 8, 7.
[question] Question. An atom has electronic configuration 2, 8, 7. (a) What is the atomic number of this element? (b) To which of the following elements would it be chemically similar? (Atomic numbers are given in parentheses.) $\mathrm{N}(7) \mathrm{F}(9) \mathrm{P}(15) \mathrm{Ar}(18)$ [/question] [solution] solution: (a) The atomic number of this element is 17. (b) It would be chemically similar to F (9) with configuration as 2, 7. [/solution]...
(a) What property do all elements in the same column of the Periodic Table as boron have in common?
[question] Question. (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? [/question] [solution] solution: (a) All the elements in the same column as boron have the same number of valence electrons (3). Hence, they all have valency equal to 3. (b) All the elements in the same column as fluorine have the same number of valence electrons (7). Hence, ...
Which element has
[question] Question. 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? [/question] [solution] solution: (a) Neon has two shells, both of which are completely filled with electrons (2 electrons in K shell and 8...
Which of the following statements is not a correct
[question] Question. Which of the following statements is not a correct statement about the trends when going from left to right across the periods of Modern Periodic Table. (a) The elements become less metallic in nature. (b) The number of valence electrons increases. (c) The atoms lose their electrons more easily (d) The oxides become more acidic. [/question] [solution] solution: (c) The atoms lose their electrons more easily. [/solution]...
By considering their position in the Modern Periodic Table,
[question] Question. By considering their position in the Modern Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic? Ga, Ge, As, Se, Be [/question] [solution] solution: Galium (Ga). [/solution]...
In the Modern Periodic Table,
[question] Question. In the Modern Periodic Table, which are the metals among the first ten elements? [/question] [solution] solution: Among the first ten elements, lithium (Li) and beryllium (Be) are metals. [/solution]...
(a) Lithium, sodium,
[question] Question. (a) Lithium, sodium, potassium are all metals that react with water to liberate hydrogen gas. Is there any similarity in the atoms of these elements? (b) Helium is an non-reactive gas and neon is a gas of extremely low reactivity. What, if anything, do their atoms have in common? [/question] [solution] solution: (a) Yes. The atoms of all the three elements lithium, sodium, and potassium have one electron in their outermost shell. (b) Both helium (He) and neon (Ne) have fille...
Name
[question] Question. Name (a) three elements that have a single electron in their outermost shells. (b) two elements that have two electrons in their outermost shells. (c) three elements with filled outermost shells. [/question] [solution] solution: (a) Lithium (Li), sodium (Na), and potassium (K) have a single electron in their outermost shells. (b) Magnesium (Mg) and calcium (Ca) have two electrons in their outermost shells. (c) Neon (Ne), argon (Ar), and xenon (Xe) have filled outermost shell...
Name two elements you would expect to show chemical reactions similar to magnesium.
[question] Question. Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice? [/question] [solution] solution: Calcium (Ca) and Strontium (Sr) are expected to show chemical reactions similar to nagnesium $(\mathrm{Mg})$. This is because the number of valence electrons $(2)$ is same in all these hree elements. And since chemical properties are due to valence electrons, they show same hemical reactions. [/solution]...
How could the Modern Periodic Table remove
[question] Question. How could the Modern Periodic Table remove various anomalies of Mendeleev’s Periodic Table? [/question] [solution] solution: Modern periodic table is based on atomic numbers whereas Mendeleev’s periodic table was based on atomic masses. So, properties of elements could be explained with more precision when elements were arranged on the basis of increasing atomic number. For example : (i) The position of isotopes is taken care of when the elements are arranged in the ascendin...
Why do you think the noble gases
[question] Question. Why do you think the noble gases are placed in a separate group ? [/question] [solution] solution: Noble gases are inert elements and thus, they do not form compounds. Their properties are different from all the other elements. Therefore, the noble gases are placed in a separate group. [/solution]...
What were the criteria used by
[question] Question. What were the criteria used by Mendeleev in creating his Periodic Table ? [/question] [solution] solution: Mendeleev’s periodic table was based on the observation that the properties of elements are a periodic function of their atomic masses. This means that if elements are arranged in the increasing order of their atomic masses, then their properties get repeated after regular intervals. [/solution]...
Besides gallium,
[question] Question. Besides gallium, which other elements have since been discovered that were left by Mendeleev in his periodic table (any two) ? [/question] [solution] solution: Scandium and germanium. [/solution]...
Use Mendeleev’s periodic table to predict
[question] Question. Use Mendeleev’s periodic table to predict the formulae for the oxides of the following elements: K, C, Al, Si, Ba. [/question] [solution] solution: Limitations of Newlands’ law of octaves: $\mathrm{K}$ is in group 1. Therefore, the oxide will be $\mathrm{K}_{2} \mathrm{O}$. $\mathrm{C}$ is in group 4 . Therefore, the oxide will be $\mathrm{CO}_{2}$. $\mathrm{Al}$ is in group $3 .$ Therefore, the oxide will be $\mathrm{Al}_{2} \mathrm{O}_{3}$. $\mathrm{Si}$ is in group 4. The...
What were the limitations
[question] Question. What were the limitations of Newlands’ Law of Octaves? [/question] [solution] solution: (i) It was not applicable throughout the arrangements. It was applicable up to calcium only. (ii) Those elements that were discovered after Newlands’ octaves did not find a place in Newlands table. (iii) The position of cobalt and nickel in the group of the elements containing F and Cl of different properties could not be explained. (iv) Placing of iron far away from cobalt and nickel, wh...
What were the limitations of Dobereiner’s classification?
[question] Question. What were the limitations of Dobereiner’s classification? [/question] [solution] solution: All known elements could not be classified into groups of triads on the basis of their properties. [/solution]...
Did Dobereiner’s triads also exist in the columns of Newlands’ Octaves?
[question] Question. Did Dobereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out. [/question] [solution] solution: Only one triad of Dobereiner's triads exists in the columns of Newlands' octaves. The triad formed by the elements $\mathrm{Li}, \mathrm{Na}$, and $\mathrm{K}$ of Dobereiner's triads also occurred in the columns of Newlands' octaves. [/solution]...