Periodic Table, Periodic Properties and Variations of Properties Class 10 ICSE | @sirtarunrupani
Sir Tarun Rupani・58 minutes read
The periodic table organizes elements based on properties like atomic number, with rows as periods and columns as groups, impacting characteristics and behavior of elements. Elements have distinct properties depending on their atomic number, influencing atomic radius, metallic character, chemical reactivity, ionization potential, electron affinity, and electronegativity, all crucial in understanding the periodic table's structure and elements.
Insights
- The periodic table was developed by scientists like Dob Yer, Newland, and Mendeleev, with Mendeleev creating the first modern table based on increasing atomic mass, grouping elements into periods and groups.
- Atomic number, the number of protons and electrons, determines an element's properties, influencing its electronic configuration and valence electrons, with the modern periodic law based on atomic number, introduced by Henry Majli.
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Recent questions
What is the periodic table?
The periodic table organizes elements based on properties.
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Summary
00:00
Evolution of the Periodic Table
- The periodic table is a table that organizes elements based on their properties, created by scientists like Dob Yer, Newland, and Mendeleev.
- Elements in the periodic table are arranged in rows and columns, with rows representing periods and columns representing groups or families.
- Dob Yer grouped elements into triads based on their atomic weights, but this method was not consistently applicable.
- Newland arranged elements in a musical octave-like pattern, where every eighth element had similar properties to the first.
- Mendeleev created the first modern periodic table based on increasing atomic mass, grouping elements into periods and groups.
- Mendeleev's periodic law was based on atomic mass, while the modern periodic law, introduced by Henry Majli, is based on atomic number.
- Atomic number, equal to the number of protons and electrons, determines an element's properties, such as its electronic configuration and valence electrons.
- The periodic table's structure includes periods (rows) and groups (columns), with elements exhibiting periodic properties at regular intervals.
- Periodic properties refer to the consistent changes in an element's properties at regular intervals across the periodic table.
- The periodic table serves as the foundation of chemistry, with atomic number being a fundamental property that influences an element's characteristics and behavior.
18:25
"Periodic Table: Elements, Groups, and Properties"
- The first 20 elements in the periodic table should be remembered in sequence, starting from hydrogen and ending at calcium.
- The periodic table consists of seven periods, with period number one at the top and period number seven at the bottom.
- Lanthanides, rare earth metals, are not part of the main periodic table to prevent it from becoming bulky.
- The group number in the periodic table indicates the valence electrons in the outermost shell of elements.
- There are 18 groups in the periodic table, with each group representing the number of electrons in the outermost shell.
- Transition elements have incomplete outer shells, leading to variable properties and multiple valencies.
- Representative elements in group 13, like boron, aluminum, and gallium, have three electrons in their last shell.
- Group number 14 elements, known as the carbon family, have four electrons in their last shell, including silicon and germanium.
- Group number 17 elements, halogens, have seven electrons in their last shell and are active non-metals that form salts.
- Group number 18 elements, noble gases, have complete outer shells and do not react with other elements.
34:13
Calcium: Group Two, Period Four, Metallic Character
- Elements are arranged by increasing atomic number, with calcium belonging to group number two.
- The group number indicates the column number, with calcium being in group two.
- Calcium is in period four, indicating it has four shells.
- Atomic radius is the distance from the nucleus to the outermost shell, increasing with more shells.
- Atomic size depends on the number of shells, with more shells leading to a larger size.
- Moving left to right across the table decreases atomic size due to increasing nuclear charge.
- Moving down the table increases atomic size as the number of shells and nuclear charge increase.
- Metallic character refers to elements that tend to lose electrons quickly.
- Metallic character decreases left to right across a period, transitioning to non-metals.
- Going down the table increases metallic character due to increasing atomic size and nuclear charge.
50:27
Chemical Reactivity Trends in Periodic Table
- Nonmetals across a period increase from left to right.
- Chemical reactivity refers to the tendency of elements to lose or gain electrons.
- Metals lose electrons, while nonmetals gain them, determining chemical reactivity.
- Chemical reactivity decreases initially across a period but later increases.
- Moving down the table, the tendency to lose electrons increases due to more shells.
- The most reactive nonmetals are found in Group 17, known as Halogens.
- Melting and boiling points of metals decrease down the table but increase for nonmetals.
- Density increases across a period due to larger atomic size and mass.
- Ionization potential increases left to right across a period due to decreasing atomic size.
- Electron affinity, the opposite of ionization potential, involves gaining electrons and releasing energy.
01:09:04
"Electronegativity: Atom's Electron Attraction Scale"
- Electronegativity is the tendency of an atom in a molecule to attract shared pairs of electrons towards itself, creating a tug of war effect.
- Linnaeus Pauling created a scale to measure electronegativity, with fluorine having the highest value of four and cesium the lowest at 0.7.
- Electronegativity increases from left to right across a period and decreases when moving down a group on the periodic table.
- Atomic number indicates the number of protons and electrons in an element, unique to each element, forming the basis of the modern periodic table.
