Element at Extreme Left In Periodic Table:
The elements of Group I-A (1) are present at extreme left of the periodic table. They are called as Alkali Metals. Alkali Metals are strong metals. These elements can easily loose their valence electron. The valence shell electronic configuration of these elements is,
ns¹
where n is principle quantum number, which shows main energy level or shell. These metals can gain Noble gas configuration (stable configuration) either by loosing one electron or by gaining seven or more electrons. As it is quite reasonable to loose one electron instead of gaining seven or more electrons so these element easily loose one electron to gain noble as configuration. The Metallic character decreases along the period from left to right. So Group II-A (2) are second most metallic elements and so on. These metals at extreme left mainly exist in solid form.
Element at Extreme Right In Periodic Table:
Elements present at extreme right of the periodic table lacks the properties of metallic character and act as non-Metals. They have almost complete outermost shell or have the deficiency of one or two electrons. They are not as hard as metallic elements and they exist with complete octet like in Noble gases, or deficient with one electron (Halogens) or two electrons (oxygen group). These elements tend to gain or accept electron if their valence shell is deficient with required number of elements. Like the valence electronic configuration of Halogens is,
ns², np⁵
So, Halogens readily accept one electron and attain noble gas configuration. Elements at extreme left exist mainly in gas phase.
Answer: The mass of electrons is mostly ignored because electrons are extremely small compared to neutrons and protons.
Explanation: A proton is about 1,836 times the size of an electron.
On the periodic table, the atomic number for each element can be found. This number is found by measuring the weight of 6.02 x 10^23 atoms of the element in grams. Electrons aren't ignored when finding exact math, but for the sake of simplification high school teachers will generally have you only count the number of protons and neutrons when calculating the mass of atoms.
Answer: it would be b time taken by the glass surface to dry
Explanation:
i had took the test and i got it right
Answer:
= 67.79 g
Explanation:
The equation for the reaction is;
4Cr(s)+3O2(g)→2Cr2O3(s)
The mass of O2 is 21.4 g, therefore, we find the number of moles of O2;
moles O2 = 21.4 g / 32 g/mol
=0.669 moles
Using mole ratio, we get the moles of Cr2O3;
moles Cr2O3 = 0.669 x 2/3
=0.446 moles
but molar mass of Cr2O3 is 151.99 g/mol
Hence,
The mass Cr2O3 = 0.446 mol x 151.99 g/mol
<u> = 67.79 g
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