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3 years ago

The most active of all the chemical elements is a halogen known as

2 answers:

5 0

I personally thought flourine. That is because it contains less outer shell electrons than the other elements. This results in the element being able to attract another electron (becoming stable) more easily.

rodikova [14]3 years ago

3 0

Astatine. Because it has the smaller shell of electrons. I believe

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Aluminum oxide (Al2O3) occurs in nature as a mineral called corundum, which is noted for its hardness and resis- tance to attack

Neko [114]

Answer:

7.03×10²³ atoms of Al

Explanation:

Corundum density = 3.97g/cm³

Corundum = Al₂O₃. Then, you have 2 moles of Al and 3 moles of O in 1 mol of the compound.

Let's determine the mass of corundum, by density

Corundum density = Corundum mass / Corundum volume

3.97 g/cm³ = Corundum mass / 15cm³

3.97 g/cm³ . 15cm³ = Corundum mass →59.55 g

Now, let's find out how many moles are in that mass of corundum

1 mol of Al₂O₃ weighs 101.96 g/mol

Then, 101.96 grams of oxide have 2 moles of Al

59.55 g of oxide, will have (59.55 .2)/101.96 = 1.17 moles

Now, we can know the quantity of atoms, by this rule of three

1 mol has NA atoms (6.02×10²³)

1.17 moles will have (1.17 . NA) = 7.03×10²³ atoms of Al

5 0

3 years ago

What are the properties of copper sulfide

Airida [17]

It is a moderate conductor of electricity, and in nature it is a dark indigo blue mineral. Density: 4.6g/cm^3. insoluble in water. melting point above 500 degrees C.

4 0

3 years ago

3<br> 3) Write any 4 important of<br> 4 important of measurement <br> Science

kramer

Answer:

A measurement is the action of measuring something, or some amount of stuff. So it is important to measure certain things right, distance, time, and accuracy are all great things to measure. Measurements can also allow us to make desicions based on the outcome of the measurement

7 0

3 years ago

How much energy must be supplied to break a single 21Ne nucleus into separated protons and neutrons if the nucleus has a mass of

love history [14]

Answer:

1)There is 2.68 * 10^-11 J of energy needed

2) The nuclear binding energy for 1 mol of Ne is 1.6 *10^13 J/mol

Explanation:

Step 1: Data given

The nucleus of a21Ne atom has a amass of 20.98846 amu.

Step 2: Calculate number of protons and neutrons

The number of electrons and protons in an 21Ne atom = 10

The number of neutrons = 21 -10 =11

Step 3: mass of the atom

Mass of a proton = 1.00727647 u

Mass of a neutron = 1.0086649 u

The mass of the atom = mass of all neutrons + mass of protons

Mass of atom = 11*1.0086649 + 10*1.00727647 = 21.1680786 amu

Step 4: Calculate change of mass

The change in mass = Mass of atom - mass of neon

Δmass = 21.1680786 - 20.98846

Δmass = 0.1796186

Step 5: Calculate mass for a single nucleus

The change of mass for a single nucleus is = Δmass / number of avogadro

Δmass of nucleus = 0.1796186 / 6.022*10^23

Δmass of nucleus =2.98 * 10^-25 grams = 2.98 * 10^-28 kg

Step 6: Calculate energy to break a Ne nucleus

Calculate the amount of energy to break a Ne nucleus

ΔEnucleus = Δmass of nucleus * c²

⇒ with c = 2.9979 *10^8 m/s

ΔEnucleus = 2.98 * 10^-28 kg * (2.9979*10^8)² = 2.68 * 10^-11 J

What is the nuclear binding energy for 1 mol of Ne?

ΔE= ΔEnucleus * number of avogadro

ΔE= 2.68 * 10^-11 J * 6.022*10^23

ΔE= 1.6 *10^13 J/mol

3 0

3 years ago

When a substance changes from gas to liquid at a temperature below its boiling point, ____ has taken place.

puteri [66]

That would be evaporation.
Hope this helped!! xx

5 0

3 years ago