Chemistry, 04.08.2019 05:30, nayelycuencax

Worth 20 explain how to use valence electrons to predict if an atom will form bonds.

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Valence electrons predict the formation of bonds based on how MANY electrons are placed on the elements outer shell.

Initially, all elements want an outer valence electron shell of 8 electrons. This is called the Octet Rule.
Here’s the key part: In order to gain those 8 valence electrons there must either be a LOSS or a GAIN in electrons. The elements that give give up their electrons are metals, while nonmetals gain the electrons that metals offer to them. This way, they’re able to form a bond together that makes them “wholesome.” (FULL 8 electron outer shell)

It’s important to keep in mind the families of the periodic table; alkali metals, alkaline earth metals, transition metals, halogens, etc,...

For example:
Oxygen is a nonmetal and has a valence electron shell of six, therefore it will want to gain two of its valence electrons to make a full outer shell.

In order to make a wholesome bond, oxygen MUST bond with an element in the Alkaline Earth Metal family in order to be whole since Alkaline Earth Metals have a valence electron outer shell of two. Being a metal, they will want to give away their two valence electrons.
Let’s just say that oxygen decided to pair with beryllium.

Therefore the bond would be;

BeO

answered: Guest

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

Write 15 uses of a mercury barometer along with its characterestics

answered: Guest

$\frac{239}{94}pu+\frac{1}{0}n ====> \frac{y}{z}x+\frac{134}{54}xe+3\frac{1}{0}$

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137 subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54 subtract 54 from both sides.

40 = z

answer

$\frac{103}{40}x=\frac{103}{40}zr$