Periodic Table Flashcards
Why were the elements arranged in the form of a table?
Because a need arose to group elements into families whose elements showed maximum resemblance.
What was observed when elements were arranged in the form of a table?
On an arrangement in the form of a table, properties of elements were seen to reappear at regular intervals in the table.
What basis of arrangement did early chemists use?
They arranged elements on basis of valency, metallic and non-metallic character
Why was the early chemists’ method discarded?
Method discarded as elements showed variable valency and dual character.
Name the scientist who arranged elements in increasing order of atomic weights and give the year.
Dobereiner in 1915 arranged elements in increasing order of their atomic weights.
What was Dobereiner’s method of arrangement?
- Elements were arranged into groups of 3 called triads.
2. Atomic weight of the middle element was found generally to be the average of the other two.
Why was Dobereiner’s method discarded?
Method discarded since it did not hold true for all elements.
Which scientist arranged elements in increasing order of atomic weights in groups of 8?
Newland, in 1864, arranged elements in increasing order of their atomic weights.
What was Newland’s method of arrangement?
- Elements were arranged in a series of 8.
2. Properties of every eight element was found to be a repetition of the 1st element.
Why was Newland’s method discarded?
Because it failed to leave spaces for undiscovered elements.
Name the scientist who arranged elements in increasing order of atomic weights into a table and give the year.
Mendeleeff, in 1869
What was Mendeleeff’s method of arrangement?
- Arranged elements in increasing order of their atomic weights.
- Elements were arranged in the form of a table called Mendeleeff’s Periodic Table.
- He stated that properties of elements were periodic functions of their atomic weights.
Why was Mendeleeff’s method discarded?
Because it could not justify the position of certain elements, rare earths and isotopes.
Which scientist arranged elements in increasing order of their atomic numbers?
Moseley in 1912
What was Moseley’s method of arrangement?
- Moseley arranged elements in increasing order of their atomic numbers.
- Elements were arranged in a modified table called modern periodic table.
- He stated that properties of elements were periodic functions of their atomic nos.
Why was Moseley’s method adopted?
This is because it removes most of the defects of Mendeleeff’s method i.e., it justifies the position of certain elements, rare earths and isotopes.
What reasons did Moseley give for modifying Mendeleeff’s periodic table?
Physical and and chemical properties of elements, depend on the no. of electrons and their arrangement & atomic no. is equal to the no. of electrons in the energy shells of an atom.
What did Moseley state which was opposite to Mendeleeff’s theory?
He stated that the basis of classification of elements be according to increasing atomic numbers and not atomic weights.
What is the fundamental property of an element?
Atomic no. is the fundamental property of an element.
Why is atomic no. the fundamental property of an element?
This is because the physical and chemical properties of an element depend on the no. of electrons and their arrangement, and atomic no. is equal to the no. of electrons in the energy shells of an atom.
What does the Modern Periodic Law state?
The MPL states that physical and chemical properties of elements are periodic functions of their at. no.
What is the arrangement of elements in the periodic table based on?
Based on the Modern Periodic Law.
Name the salient features of the Modern Periodic Table?
- Classification
- Position
- Methodical Arrangement
- Separation of Elements
- Periodicity of Elements
Elaborate on how classification is a salient feature of the MPT.
Period table is based on basic fundamental property - atomic no.
Elaborate on how position is a salient feature of the modern periodic table.
The MPT arranges elements in increasing the order of atomic numbers in seven horizontal rows called periods and eighteen vertical columns called groups.
Why is the completion of each period logical?
Since each period begins with an element having one electron in outermost shell and ends with zero group element having completely filled outermost shell.
What transition is seen across a period?
A transition from metallic to non-metallic character is seen across a period.
What is common between each vertical column?
Each vertical column accommodates elements with the same electronic configuration, thus having similar properties.
Which groups are called normal elements?
Groups 1, 2 & 13 to 17 [I Ato VII A] are called normal elements.
Which groups are called transition elements?
Groups 3 to 12 [I B to VII B & VIII] are called transition elements.
Which group contains noble or inert gases?
Group 18[zero] at extreme right contains noble gases.
Elaborate on the separation of metals in the MPT
- Reactive metals are placed in group 1[I A] and 2 [II A].
- Transition elements (metals) are placed in the middle.
- Non-metals are placed in the upper right corner of the periodic table.
What is periodicity of elements?
Gradual change in properties is seen with increases in atomic number in the periodic table.
What is periodicity in properties?
Recurrence in properties with elements belonging to same subgroup in the periodic table after a difference of 2,8, 18 or 32 in atomic numbers due to recurrence of similar valence shell electronic configuration is called periodicity in properties.
Define a period in the MPT.
A period is a horizontal row of elements arranged in increasing order of atomic numbers.
How many periods are there in the periodic table?
7 periods in the MPT
What does the period no. signify?
The period no. signifies the no. of electrons shells of an element.
Which are the short periods? Why?
Periods 1,2 and 3 are the short periods. Period 1 has only 2 elements, and periods 2 and 3 both have 8 elements.
Which are the long periods?
Periods 4,5,6 and 7 are the long periods with 18 , 18, 32 and 26 elements respectively.
In which period does the Lanthanide series fall?
In period 6
In which period does the actinide series fall?
In period 7
What are bridge elements?
Bridge elements are those which show similarities in properties diagonally with the period of the next group.
In which period are bridge elements found?
Bridge elements are found in period 2.
Name the bridge elements which show similarity with typical elements
Li, Be, B , C
Which typical element does Li sho similarity in properties with?
Li (atomic no. 3) shows similarity with Mg (at. no. 12)
Which typical element does Be show similarity in properties with?
Be (At. no. 4) shows similarity with Al (At. no. 13)
Which typical element does B show similarity in properties with?
B (at. no. 5) shows similarity with Si (at. no. 14).
What remains same across a period?
No. of electrons shells remains same across a period.
Which shells do electrons enter in period 1?
Electrons enter K shell in period 1
Which shell do electrons enter in period 2?
Electrons enter L shell in period 2.
M shell in period 3, and so on.
What increases across a period?
The no. of valence electrons increases by one across a period. Consequently, there is a transition from metallic to non-metallic character.
Non-metallic character _ across a period.
increases
Name the chlorides which are solid and have ionic bonding.
- Sodium chloride (NaCl)
- Magnesium chloride (MgCl2)
- Aluminium chloride (AlCl3)
Nam the chloride which is solid and goes through both ionic and covalent bonding.
Aluminium chloride (AlCl3) goes through both ionic and covalent bonding and is solid.
Name the chlorides which are liquid and go through covalent bonds.
- Silicon tetrachloride (SiCl4)
- Phosphorous trichloride
- Phosphorus pentachloride
- Disulphur dichloride
Name a chloride which can either be liquid or solid but goes through covalent bonding.
Phosphorus trichloride or phosphorus pentachloride
Name a basic oxide that goes through electrovalent bonding.
Magnesium oxide (MgO)
Name an amphoteric oxide that goes through electrovalent bonding.
Aluminium oxide (Al2O3)
Name a weakly acidic oxide that goes through covalent bonding.
silicon dioxide (SiO2)
Name three acidic oxides that go through covalent bonding.
Phosphorous pentoxide (P2O5) Sulphur dioxide (SO2) Sulphur trioxide (SO3)
Name a strongly acidic oxide that goes through covalent bonding.
Chlorine heptoxide (Cl2O7)
Name a hydroxide that is a strong base.
Sodium hydroxide (NaOH)
Name a hydroxide that is a weak base.
Magnesium hydroxide (Mg(OH)2)
Name a hydroxide that is amphoteric
Aluminium hydroxide (Al(OH3))
What is an oxyacid?
An oxyacid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element.
Name three oxyacids which is a weak acid.
- Metasilicic acid (H₂SiO₃)
- Metaphosphoric Acid (HPO3
- Orthophosphoric acid ( H₃PO ₄)
Name three oxyacids that are strong acids.
- Sulphurous acid (H₂SO₃)
- Sulphuric acid (H₂SO₄)
- Perchloric acid (HClO₄)
What is a hydride?
In compounds that are regarded as hydrides, the hydrogen atom is bonded to a more electropositive element or group.
Name a hydride that is a strong base.
Sodium hydride (NaH)
Name a hydride that is a weak base.
Magnesium hydride (MgH₂)
Name three hydrides that are weaker bases.
- Aluminium hydride (AlH₃)
- Silane (SiH₄)
- Phosphine (PH₃)
Name a hydride that is a weak acid.
Hydrogen sulphide (H ₂S)
Name a hydride that is a strong acid.
Hydrochloric acid (HCl)
Name a strongly basic oxide that goes through electrovalent bonding.
Sodium oxide (Na2O)
What transition is seen across period 2 with reference to the valency?
The valency of the elements in period 2 increases from 1 to 4, 1 being a metal Lithium, 3 being a metalloid Boron, 4 being a non-metal Carbon. Then it decreases from 3 to 0, 3 being nitrogen and 0 being neon.
Increases from 1 to 4, then 3 to 0
Name the metals present in period 2.
Lithium and Beryllium
Name the non-metals present in period 2.
Carbon, Nitrogen, Oxygen, Fluorine
Name the metalloid present in period 2
Boron
Name the noble gas present in period 2.
Neon
Name the two elements present in period 1.
Hydrogen [H-group 1(I A)] & Helium [ 2He - group 18 (0)]
Name the metals present in period 3 with their valency.
Sodium - Valency 1
Magnesium - Valency 2
Aluminium - Valency 3
Name the metalloid in period 3, along with valency.
Silicon - Valency 4
Name the non-metals in period 3.
Phosphorus - Valency 3
Sulphur - Valency 2
Chlorine - Valency 1
Which is the noble gas in period 3?
Argon - Valency 0
How many groups in the periodic table?
There are eighteen vertical columns - [with eight main groups] in the periodic table.
What does the group no. signify?
Group no. signifies the no. of valence electrons of an element, which are electrons present in the outermost shell of an element.
How many valence electrons do transition elements have?
2 valence electrons
Which type of elements does group 1 contain?
Group 1 [I A] contains alkali metals.
Which elements does group 1[I A] contain?
(Light metals) Li (At. no. 3) to Francium (At. no. 87)
Which type of elements does group 2 [II A] contain?
Group 2[II A] contains alkaline earth metals.
Which elements does group 2[II A] contain?
(Light metals) From Beryllium (At. No. 4) to Radium (At. No. 88)
What type of elements do group 3 to 12 contain?
Groups 3 to 12 contain transition elements.
Which are the transition elements & which groups are they in?
The transition elements are Scandium (At. No. 21) to Zinc (At. No. 30) in groups 3 to 12. These are heavy metals.
Which are the inner transition elements & which groups are they in?
The inner transition elements range from Yttrium [Y] (At No. 39) to Cadmium [Cd] (At. No. 48). They are in the groups IB to VIIB, VIII
Which series is found in period 6 and groups 3 to 12?
The lanthanide series is found in period 6. It ranges from the elements Cerium [Ce] (At. No. 58) to Lutetium [Lu] (At. No. 71)
What is the sequence of elements in period 6 and groups 3 to 12?
Lanthanum [La] (At. No. 57); Ce (58) to Lu (71); Hafnium [Hf] (At. No. 72) to Mercury [Hg] (80).
Which series is found in period 7 and groups 3 to 12?
The actinide series is found in period 7. It ranges from the elements Thorium [Th] (At. No. 90) to Lawrencium [Lr] (At. No. 103)
What is the sequence of elements in period 7 and groups 3 to 12?
Actinium [Ac] (At. No. 89); Th (90) to Le (103); Rutherfordium[Rf] (At. No. 104) to Copernicium [Cn] (112).
What type of elements do group 13 to 16 contain?
They contain post transition elements, from IIIA to VIA.
What is the range of elements in groups 13 to 16?
Aluminium [Al] (13) to Thallium [Ti] (81)
Germanium [Ge] (32) to Lead [Pb] (82)
Antimony [Sb] (51) to Bismuth [Bi] (83)
Polonium [Po] (84)