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Question: 1
What are blocks. How many blocks are present in periodic table?
Answer: 1
1-40On the basis of completion of a particular sub shell, elements with similar sub-shell electronic configuration are referred as a block of elements. Four blocks are present in periodic table.s.p.d.f
Question: 2
Define Modern Periodic law.
Answer: 2
2-40In 1913 H.Moseley give modern periodic law
"Properties of elements are periodic function of their atomic number".
Question: 3
Define Periods?
Answer: 3
3-40Seven horizontal rows present in periodic table are called periods. Numbered from 1 to 7.
Question: 4
Define Mendeleev's Periodic law.
Answer: 4
4-40A Russian chemist arranged elements (63) discovered at that time according to increasing atomic mass. "Properties of elements are periodic function of their atomic masses".
Question: 5
Give the trend of ionization energy in a period?
Answer: 5
5-40If we move from left to right in a period the value of ionization energy increases. Because the size of atom reduce and valence electrons are held strongly by the electrons are held strongly by the electrostatic force of nucleus. Therefore elements on left side of the periodic table have low ionization energies as compared to those on right side of the periodic table.
Question: 6
Why Cesium requires little energy to release its one electron present in the their outermost shell?
Answer: 6
6-40Cesium is the 2nd last element of 1st group . It has large size and less force of attraction between the nucleus and valence electron, as a result small amount of energy is required to remove electron from the valence shell
Question: 7
Why the size of atom does not decrease regularly in periods?
Answer: 7
7-40The atomic size does not decrease regularly in periods due to presence of transition elements. The size of atom first decreases then increases.
Question: 8
Waht are Dobereiner's Triads?
Answer: 8
8-40A German chemist Dobereiner observed relationship between atomic masses of several groups of three elements called Triads. In triads the central and middle element had atomic mass average of the other two elements.
Question: 9
Why shielding effect of electron makes action formation easy?
Answer: 9
9-40As we move down in a group more and more shells come between valence shell and the nucleus of atom, additional shell reduce the electrostatic force of attraction felt by teh electron present in the outermost shell, and the shielding effect increases resultantly, and electrons can be taken away, easily and cations form.
Question: 10
Why noble gases are not reactive?
Answer: 10
10-40Nobel gases are not reactive because they do have 2 or 8 electrons in their valence shell Mean all nobel gases have completely filled valence shell. Their atoms do not have vacant space to accommodate extra electrons. Therefore, nobel gases do not gain, lose or share electrons.
Question: 11
What do you mean by group and periods in the periodic table?
Answer: 11
11-40The Horizontal rows in periodic table called periods and vertical columns in the periodic table are called group.
Question: 12
How many elements are placed in first period and what are their names and symbols.
Answer: 12
12-40There are two elements in first period, Hydrogen (H), Helium(He)
Question: 13
Define groups?
Answer: 13
13-40Seven horizontal rows present in periodic table are called periods. Numbered from 1 to 7.
Question: 14
Who introduced the name periodic table?
Answer: 14
14-40Mendeleev introduced name of periodic table.
Question: 15
Why do the bigger size atoms have more shielding effect?
Answer: 15
15-40In bigger size atoms the number of inner shells and inner shell electrons increases hence the shielding effect in bigger size molecules also increases.
Question: 16
Why ionization energy of Na is less than Ma?
Answer: 16
16-40Ionization energy is the energy required to remove the most loosely bound electron from an atom. As the nuclear charge of an atom increases as more energy is required to remove an electron. Mg atom has a smaller redius and higher nuclear charge than Na atom, thus more energy will requireto remove the electron from the same orbital (3s), making the first ionization energy of Mg higher than that of Na .
Question: 17
Why do atoms react?
Answer: 17
17-40Those elements which do not have complete octel and duplet. They react with other element to complete valence shell by losing or gaining of electrons.
Question: 18
How many elements are there in 4period?
Answer: 18
18-40The fourth period contains 18 elements, beginning with potassium and ending with krypton.
Question: 19
What is effective nuclear charge?
Answer: 19
19-40The valence electron of an atom experiences less nuclear change than that of actual charge . It is called effective nuclear charges of Z
Question: 20
Describe Ionization energy.
Answer: 20
20-40The ionization energy is the amount of energy required to remove the most loosely bound electron from the valence shell of an isolated gaseous atom.
Question: 21
Write down the names of clements of groups I with their symbols.
Answer: 21
21-401st group elements are called alkali metals. It consists of hydrogen , (H). Lithium(Li), Sodium (Na) , Potassium(K), Rubidium (Rb) and Cesium(Cs) and Francium(Fr)
Question: 22
What are SI units of atomic radius?
Answer: 22
22-40Pico meter
Question: 23
Distinguish between period and group in periodictable.
Answer: 23
23-40Groups and periods are two way of categorizing elements on the periodic table. Periodic table. Periods are horizontal rows in the periodic table while groups are vertical columns in the table.
Question: 24
Define electron affinity.
Answer: 24
24-40Amount of energy releases when an electron is added up in the outer most shell of an isolated gaseous atom is called electron affinity.
Question: 25
Write down drawbacks of Mendeleev's periodic table?
Answer: 25
25-401-In some cases element of higheratomic masses are placed before those having lower atomic masses.
2- No attempt has been made to place metals and non-metals separately in it.
Question: 26
Define Periodicity.
Answer: 26
26-40Properties of elements were found repeating after regular after regular intervals in periodic tabel it is the periodicity.
Question: 27
What are Lanthanide and Actinide series?
Answer: 27
27-40Due to space problem two series of elements are placed below periodic table.
Lanthanide: Series of elements starts from Lanthanum(Z=57) Called Lanthanide series.
Actinide: Sereis of element starts from Actinium(Z-89) called actinide series.
Question: 28
Define Atomic Radius.
Answer: 28
28-40"The half of the distance between the nuclei of the two bonded atoms referred as atomic radius".
Example: Distance between the nuclei of two carbon atoms in elemental form is 154 pm its half is 77 pm. Which is atomic radius of Carbon.
Question: 29
Describe Newland of octaves
Answer: 29
29-40According to Newland law of octaves when the elements are arranged in order go increasing atomic weight, then every eight elements Has properties similar to that of the first element
Question: 30
Define Ionization Energy.
Answer: 30
30-40"The ionization energy is the amount of energy required to remove the most loosely bond electron from the valence shell of an isolated gaseous atom.
Question: 31
How many periods are considered normal periods?
Answer: 31
31-402nd and 3rd periods are normal periods.
Question: 32
Define electron affinity with an example.
Answer: 32
32-40Electron affinity is defined as the amount of energy released when an electron is added in the outermost shell of an isolated gaseous atom.
Example:
The first electron affinity of chlorine is -349kJmole-²
Question: 33
Why the elements are called s and p block elements?
Answer: 33
33-40The elements having their valence electrons in s and p sub shell called s and p blocks elements.
Question: 34
How many elements are placed in 4th period?
Answer: 34
34-40Eighteen elements are present
Question: 35
What are the elements arranged in group 3 to 12 called?
Answer: 35
35-40Elementof group 3 to 12 in a modern periodic table are called d-block elements
Question: 36
Write any four properties of the long form periodictable.
Answer: 36
36-401-It shows arrangement of elements based on modern periodic law.
2- There are 18 vertical columns known as groups
3- There are 7 horizontal row known as periods Elements having similar outer electronic configurations
Question: 37
Define atomic size and atomic radius
Answer: 37
37-40Atomic size is the distance between a nucleus of an atom and its valence or outermost shell . and half of the distance between the nuclei of the two bonded atom is known as atomic radius
Question: 38
What is meant by periodic function?
Answer: 38
38-40When any property, whether its chemical or physical of all periodic table elements repeats after a fixed number of elements in increasing atomic number it is referred as periodic function.
Question: 39
Define Mendleev's periodic law
Answer: 39
39-40Question: 40
Explain Dobereiner's triads
Answer: 40
40-40A German chemist Dobereiner observed relationship between atomic masses of several groups of three elements called triads. In these groups, the central or middle element had atomic mass average of the other two elements
