Why Do Elements in the Same Family Generally Have the Same Properties
Learning Objective
- Draw the general trends of physical backdrop within a group on the periodic tabular array.
Key Points
- The concrete backdrop of elements depend in part on their valence electron configurations. Equally this configuration remains the same within a group, physical properties tend to remain somewhat consistent.
- The most notable inside-group changes in concrete properties occur in Groups 13, fourteen, and 15, where the elements at the meridian are non-metallic, while the elements at the bottom are metals.
- The trends in boiling and melting points vary from group to group, based on the blazon of not-bonding interactions holding the atoms together.
Terms
- ductileCapable of being pulled or stretched into thin wire past mechanical forcefulness without breaking.
- physical propertyAny property that is measurable whose value describes a concrete organisation'southward state.
- malleableAble to be hammered into sparse sheets; capable of existence extended or shaped by beating with a hammer or by the pressure of rollers.
In chemistry, a grouping is a vertical cavalcade in the periodic table of the chemic elements. In that location are 18 groups in the standard periodic tabular array, including the d-block elements merely excluding the f-cake elements. Each chemical element within a group has similar physical or chemic properties because of its atom's outermost electron shell (nearly chemical properties are dominated past the orbital location of the outermost electron).
Common Physical Properties
A physical property of a pure substance can be defined every bit annihilation that can be observed without the identity of the substance changing. The observations usually consist of some blazon of numerical measurement, although sometimes there is a more qualitative (non-numerical) clarification of the property. Physical backdrop include such things as:
- Color
- Brittleness
- Malleability
- Ductility
- Electrical conductivity
- Density
- Magnetism
- Hardness
- Atomic number
- Specific heat
- Heat of vaporization
- Estrus of fusion
- Crystalline configuration
- Melting temperature
- Humid temperature
- Oestrus electrical conductivity
- Vapor force per unit area
- Tendency to dissolve in diverse liquids
These are only a few of the measurable concrete properties.
Within a group of the periodic tabular array, each element has the aforementioned valence electron configuration. For example, lithium, sodium, potassium, rubidium, cesium, and francium all take a unmarried electron in an s orbital, whereas every element in the grouping including fluorine has the valence electron configuration ns2npfive, where north is the period. This means the elements of a group oftentimes exhibit similar chemical reactivity, and there may exist similarities in concrete backdrop every bit well.
Boiling and Melting Points
Before a discussion of the melting points of various elements, it should be noted that some elements be in unlike forms. For example, pure carbon can exist as diamond, which has a very high melting point, or as graphite, whose melting signal is still loftier just much lower than that of diamond.
Different groups exhibit different trends in boiling and melting points. For Groups 1 and 2, the boiling and melting points decrease as you move down the group. For the transition metals, boiling and melting points mostly increase every bit you move down the grouping, but they decrease for the zinc family unit. In the chief group elements, the boron and carbon families (Groups thirteen and 14) subtract in their boiling and melting points as y'all move downwardly the grouping, whereas the nitrogen, oxygen, and fluorine families (Groups 15, xvi, and 17) tend to increase in both. The noble gases (Group eighteen) decrease in their boiling and melting points downwards the group.
These phenomena can be understood in relation to the types of forces holding the elements together. For metallic species, the metallic bonding interaction (electron-sharing) becomes more hard as the elements get larger (toward the bottom of the table), causing the forces holding them together to become weaker. As you move right forth the table, nevertheless, polarizability and van der Waals interactions predominate, and equally larger atoms are more polarizable, they tend to exhibit stronger intermolecular forces and therefore college melting and boiling points.
Metallic Graphic symbol
Metallic elements are shiny, usually gray or silver in color, and conductive of heat and electricity. They are malleable (can be hammered into sparse sheets) and ductile (can be stretched into wires). Some metals, such as sodium, are soft and tin can be cutting with a pocketknife. Others, such as iron, are very hard. Non-metallic atoms are dull and are poor conductors. They are breakable when solid, and many are gases at STP (standard temperature and pressure). Metals give abroad their valence electrons when bonding, whereas non-metals tend to accept electrons.
Metallic character increases from right to left and from pinnacle to bottom on the table. Non-metallic character follows the opposite pattern. This is considering of the other trends: ionization energy, electron analogousness, and electronegativity. You will notice a jagged line running through the periodic table starting between boron and aluminum – this is the separation between metallic and not-metal elements, with some elements close to the line exhibiting characteristics of each. The metals are toward the left and heart of the periodic table, in the s, d, and f blocks. Poor metals and metalloids (somewhat metal, somewhat non-metallic) are in the lower left of the p block. Not-metals are on the right of the tabular array.
Source: https://courses.lumenlearning.com/introchem/chapter/variation-of-physical-properties-within-a-group/
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