Why Do Elements in the Same Family Generally Have Similar Properties?
Learning Objective
- Describe the general trends of concrete backdrop within a grouping on the periodic table.
Central Points
- The concrete properties of elements depend in part on their valence electron configurations. As this configuration remains the same within a group, physical properties tend to remain somewhat consistent.
- The most notable inside-grouping changes in concrete properties occur in Groups 13, 14, and 15, where the elements at the summit are not-metallic, while the elements at the lesser are metals.
- The trends in boiling and melting points vary from group to group, based on the type of non-bonding interactions belongings the atoms together.
Terms
- ductileCapable of being pulled or stretched into thin wire by mechanical force without breaking.
- physical propertyAny belongings that is measurable whose value describes a physical system'southward state.
- malleableAble to exist hammered into thin sheets; capable of being extended or shaped by beating with a hammer or by the pressure of rollers.
In chemistry, a group is a vertical column in the periodic table of the chemical elements. There are 18 groups in the standard periodic table, including the d-cake elements just excluding the f-block elements. Each element within a grouping has similar physical or chemic properties because of its cantlet's outermost electron shell (well-nigh chemical backdrop are dominated by the orbital location of the outermost electron).
Mutual Physical Properties
A physical property of a pure substance can exist defined as anything that can exist 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 (not-numerical) description of the holding. Physical backdrop include such things as:
- Color
- Brittleness
- Malleability
- Ductility
- Electric conductivity
- Density
- Magnetism
- Hardness
- Atomic number
- Specific estrus
- Heat of vaporization
- Estrus of fusion
- Crystalline configuration
- Melting temperature
- Boiling temperature
- Heat electrical conductivity
- Vapor pressure
- Tendency to dissolve in diverse liquids
These are but a few of the measurable physical properties.
Within a group of the periodic table, each element has the same valence electron configuration. For case, lithium, sodium, potassium, rubidium, cesium, and francium all take a single electron in an s orbital, whereas every element in the group including fluorine has the valence electron configuration ns2np5, where due north is the menstruum. This means the elements of a grouping frequently exhibit similar chemical reactivity, and there may be similarities in physical properties likewise.
Boiling and Melting Points
Before a word of the melting points of various elements, it should be noted that some elements exist in different forms. For example, pure carbon tin can be as diamond, which has a very high melting point, or as graphite, whose melting point is still high but much lower than that of diamond.
Different groups exhibit different trends in boiling and melting points. For Groups 1 and two, the humid and melting points decrease as you move down the group. For the transition metals, boiling and melting points mostly increment as you lot move down the grouping, but they decrease for the zinc family. In the main grouping elements, the boron and carbon families (Groups 13 and fourteen) decrease in their boiling and melting points as you move down the grouping, whereas the nitrogen, oxygen, and fluorine families (Groups xv, 16, and 17) tend to increase in both. The noble gases (Grouping 18) decrease in their boiling and melting points downwards the group.
These phenomena tin can exist understood in relation to the types of forces holding the elements together. For metallic species, the metallic bonding interaction (electron-sharing) becomes more difficult every bit the elements go larger (toward the bottom of the tabular array), causing the forces holding them together to go weaker. Equally you move right forth the table, all the same, polarizability and van der Waals interactions predominate, and as larger atoms are more than polarizable, they tend to exhibit stronger intermolecular forces and therefore higher melting and humid points.
Metallic Character
Metal elements are shiny, usually gray or silver in color, and conductive of oestrus and electricity. They are malleable (can be hammered into sparse sheets) and ductile (can be stretched into wires). Some metals, such every bit sodium, are soft and can be cut with a knife. Others, such as iron, are very hard. Not-metallic atoms are tiresome and are poor conductors. They are brittle when solid, and many are gases at STP (standard temperature and pressure). Metals give away their valence electrons when bonding, whereas non-metals tend to take electrons.
Metallic character increases from right to left and from top to lesser on the table. Not-metallic character follows the opposite pattern. This is because of the other trends: ionization energy, electron affinity, and electronegativity. You will notice a jagged line running through the periodic table starting betwixt boron and aluminum – this is the separation between metallic and non-metallic elements, with some elements close to the line exhibiting characteristics of each. The metals are toward the left and center of the periodic tabular array, in the s, d, and f blocks. Poor metals and metalloids (somewhat metallic, somewhat non-metal) are in the lower left of the p block. Not-metals are on the correct of the table.
Source: https://courses.lumenlearning.com/introchem/chapter/variation-of-physical-properties-within-a-group/
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