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2 years ago

Why on moving from left to right in a period the chemical reactivity of element first decreases and then increases?

1 answer:

4 0

This phenomenon is known as the periodic trends in reactivity. It occurs because of the arrangement of electrons in orbitals.

As one moves from left to right across a period, the number of electrons in the outermost shell increases. These outermost electrons are involved in chemical reactions.

Therefore, as the number of outermost electrons increases, the reactivity of the element increases. However, the elements have filled shells, so beyond a certain point, the outermost shell will be full.

The reactivity then decreases as the electrons are no longer available to take part in chemical reactions. Therefore, the reactivity of the elements decreases from left to right in a period and then increases as the outermost shell begins to fill up again.

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What is relative isotopic mass

lidiya [134]

Answer:

Relative atomic mass or atomic weight is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a given sample to the atomic mass constant. The atomic mass constant is defined as being 1/12 of the mass of a carbon-12 atom.

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3 years ago

1. Explain why the cold water and hot water in Part 1 moved the way they did within the tub of

neonofarm [45]

Answer:

Cooling a substance causes molecules to slow down and get slightly closer together, occupying a smaller volume that results in an increase in density. Hot water is less dense and will float on room-temperature water. Cold water is more dense and will sink in room-temperature water.

5 0

3 years ago

The___ of an element is the number of

castortr0y [4]

Answer:atomic mass, neutrons in the nucleus

Explanation: because I remember from when I took honors chemistry last year we learned about this and it’s called the atomic mass when looking at an atom and the neutrons in the nucleus are effected by it.

8 0

3 years ago

: An unknown metal crystallizes in the cubic crystal structure. The metal has a radius 140pm, atomic mass of 135 g/mol, and dens

ki77a [65]

The cubic unit cell this metal crystallize as is BCC structure .

The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest repeating unit, which is referred to as its unit cell.

The unit cell consists of lattice points that represent the locations of atoms or ions.

The entire structure then consists of this unit cell repeating in three dimensions

$\rm \rho =\dfrac{nM}{N_{0} a^{3}} \\\\\\\\\rm n =\dfrac{\rho N_{0} a^{3}}{M} \\\\\\\\Assuming\; it \; to \; be \; a\; BCC\; structure \\\\\\ r = \dfrac{\sqrt{3} \times a}{4} \\\\\\Therefore\; a = 3.23 \times 10^{-8}\\\\\\\\\rm n =\dfrac{13.3 \times 6.022 \times 10^{23}\times 3.23^{3}\times (10^{-8})^{3}}{135} \\\\$

n= 2

Hence our assumption was correct

It is a BCC structure .

Therefore the cubic unit cell this metal crystallize as is BCC structure .

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2 years ago

A gas sample occupies 350.0 mL at 546 mm Hg. What volume does the gas occupy at 652 mm Hg?

leva [86]

Answer:

293.1 mL.

Explanation:

Boyle's law states that: at a constant temperature the pressure of a given mass of an ideal gas is inversely proportional to its volume.

It can be expressed as: P₁V₁ = P₂V₂,

P₁ = 546.0 mm Hg, V₁ = 350.0 mL.

P₂ = 652.0 mm Hg, V₂ = ??? mL.

∴ V₂ = (P₁V₁)/(P₂) = (546.0 mm Hg)(350.0 mL) / (652.0 mm Hg) = 293.1 mL.

8 0

3 years ago