explain the trends in a periodic table

explain the trends in a periodic table


3 Answers

Ashutosh Sharma
askIITians Faculty 181 Points
8 years ago
Electronegativity-itcan be understood as achemical property describing an atom's ability to attract and bind withelectrons.
From left to right across a period of elements, electronegativity increases,If the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one. Conversely, if the valence shell is more than half full, it is easier to pull an electron into the valence shell than to donate one.
From top to bottomdown a group, electronegativity decreases,This is because atomic number increases down a group, and thus there is an increased distance between the valence electrons and nucleus, or a greater atomic radius.
exceptions of the above rules include the noble gases,lanthanides, andactinides.The noble gases possess a complete valence shell and do not usually attract electrons. The lanthanides and actinides possessmore complicated chemistry that does not generally follow any trends. Therefore, noble gases, lanthanides, and actinides do not have electronegativity values.
Ionization Energy​​-itis theenergy required to remove an electron from a neutral atom in its gaseous phase.
The ionization energy of the elements within a period generallyincreasesfrom left to right.This is due to valence shell stability.
The ionization energy of the elements within a group generallydecreasesfrom top to bottom.This is due to electron shielding.
The noble gases possess very high ionization energies because of their full valence shells.
Electron Affinity-itisthe ability of an atom to accept an electron. Unlike electronegativity, electron affinity is a quantitative measurement of the energy change that occurs when an electron is added to a neutral gas atom. The more negative the electron affinity value, the higher an atom's affinity forelectrons.
Electron affinityincreasesfrom left to rightwithin a period because of the decrease in atomic radius.
Electron affinitydecreasesfrom top to bottomwithin a group because of the increase in atomic radius.
Atomic Radius-The atomic radius is one-half the distance between the nuclei of two atoms.
Atomic radiusdecreasesfrom left to rightwithin a period because of the increase in the number of protons and electrons across a period. One proton has a greater effect than one electron; thus,electrons are pulled towards the nucleus, resulting in a smaller radius.
Atomic radiusincreasesfrom top to bottomwithin a group because of the electron shielding.
Melting Point-The melting points is the amount of energy required to break a bond(s) to change the solid phase of a substance to a liquid.
Metals generally possess ahigh melting point.
Most non-metals possesslow melting points.
Metallic Character-The metallic character of an element can be defined as how readily an atom can lose an electron.
Metallic characteristicsdecreasefrom left to right across a period.This iscaused by the decrease in radius(caused by Zeff, as stated above)of the atom that allows the outer electrons to ionize more readily.
Metallic characteristicsincreasedown a group.Electron shielding causes the atomic radius to increase thus the outerelectrons ionizesmore readily than electrons in smaller atoms.

50 Points
8 years ago
thanks a lott!!
it really helped me
Prajwal Kavad
603 Points
8 years ago
first read NCERT textbook it has everything

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