In a similar way, graphite a non-metal also has delocalised electrons. However, you don't see the idea that it consists of carbon ions. The giant lattice structure of silicon is similar to that of diamond.
Each silicon atom is covalently bonded to four other silicon atoms in a tetrahedral arrangement. All Rights Reserved. Electrical conductivity across period 3. Learning outcomes After studying this page, you should be able to: describe and explain how electrical conductivity varies across period 3. The attractions and therefore the melting and boiling points increase because:. Silicon has high melting and boiling points due to its network covalent structure.
Melting or boiling silicon requires the breaking of strong covalent bonds. Because of the two different types of bonding in silicon and aluminum, it makes little sense to directly compare the two melting and boiling points. Phosphorus, sulfur, chlorine and argon are simple molecular substances with only van der Waals attractions between the molecules. Their melting or boiling points are lower than those of the first four members of the period which have complex structures.
The magnitudes of the melting and boiling points are governed entirely by the sizes of the molecules, which are shown again for reference:. Jim Clark Chemguide. Electronic structures Across Period 3 of the Periodic Table, the 3s and 3p orbitals fill with electrons. Below are the abbreviated electronic configurations for the eight Period 3 elements: Na [Ne] 3s 1 Mg [Ne] 3s 2 Al [Ne] 3s 2 3p x 1 Si [Ne] 3s 2 3p x 1 3p y 1 P [Ne] 3s 2 3p x 1 3p y 1 3p z 1 S [Ne] 3s 2 3p x 2 3p y 1 3p z 1 Cl [Ne] 3s 2 3p x 2 3p y 2 3p z 1 Ar [Ne] 3s 2 3p x 2 3p y 2 3p z 2 In each case, [Ne] represents the complete electronic configuration of a neon atom.
The pattern of first ionization energies across Period 3 There is a general upward trend across the period, but this trend is broken by decreases between magnesium and aluminum, and between phosphorus and sulfur.
Explaining the pattern First ionization energy is dependent on four factors: the charge on the nucleus; the distance of the outer electron from the nucleus; the amount of screening by inner electrons; whether the electron is alone in an orbital or one of a pair. Atomic radius The diagram below shows how atomic radius changes across Period 3.
The figures used to construct this diagram are based on: metallic radii for Na, Mg and Al; covalent radii for Si, P, S and Cl; the van der Waals radius for Ar which forms no strong bonds. Explaining the Trend A metallic or covalent radius is a measure of the distance from the nucleus to the bonding pair of electrons. Electronegativity Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.
The trend The trend across Period 3 looks like this: Argon is not included; because it does not form covalent bonds, its electronegativity cannot be assigned. Explaining the Trend The explanation is the same as that for the trend in atomic radii. Physical Properties This section discusses electrical conductivity and the melting and boiling points of the Period 3 elements.
Structures of the elements The structures of the elements vary across the period. Three metallic structures Sodium, magnesium and aluminum all have metallic structures. A network covalent structure Silicon has a network covalent structure like that of diamond. A representative section of this structure is shown: The structure is held together by strong covalent bonds in all three dimensions. Four simple molecular structures The structures of phosphorus and sulfur vary depending on the type of phosphorus or sulfur in question.
These structures are shown below: Aside from argon, the atoms in each of these molecules are held together by covalent bonds. Below is an electrical circuit to demonstrate the electrical conductivity of Period 3 elements. Tip: To turn text into a link, highlight the text, then click on a page or file from the list above. This Sidebar appears everywhere on your workspace. Add to it whatever you like -- a navigation section, a link to your favorite web sites, or anything else.
Get a free wiki Try our free business product. Electrical Conductivity Page history last edited by Liu Shuyu 9 years ago. E Electrical Conductivity Trend : Across the period Na to Ar , electrical conductivities of the elements are as shown. Many salts are halides; the hal- syllable in halide and halite reflects this correlation. All Group 1 metals form halides that are white solids at room temperature. The melting point is correlated to the strength of intermolecular bonds within the element.
First, we must analyze compounds formed from elements from Groups 1 and 2 e. To develop an understanding of bonding in these compounds, we focus on the halides of these elements.
The physical properties of the chlorides of elements in Groups 1 and 2 are very different compared to the chlorides of the elements in Groups 4, 5, and 6.
All of the alkali halides and alkaline earth halides are solids at room temperature and have melting points in the hundreds of degrees centigrade. The non-metal halide liquids are also electrical insulators and do not conduct electrical current. In contrast, when an alkali halide or alkaline earth halide melts, the resulting liquid is an excellent electrical conductor. This tells us that these molten compounds consist of ions, whereas the non-metal halides do not.
This again demonstrates the type of bonding that these compounds exhibit: the left-most elements form more ionic bonds, and the further-right elements tend to form more covalent bonds.
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