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3 years ago

I need helpon science ASAP will bive brainlist

Chemistry

1 answer:

frosja888 [35]3 years ago

3 0

Answer:

Explanation:

it is a trench so if they went together then they would rise up but if they missed then it would create a hole

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Some alkenes have geometric (cis-trans) isomers because ________. all of the carbon atoms in the compound are rigid and cannot r

faust18 [17]

Answer:

the carbon atoms in the double bond cannot rotate

Explanation:

Isomers refer to molecules that have a distinct arrangement of the atoms in the molecule but have the same molecular formula.

Alkenes refer to a series of unsaturated hydrocarbons that contain ethylene and propylene.

Some alkenes have geometric (cis-trans) isomers because <u>the carbon atoms in the double bond cannot rotate</u>.

7 0

3 years ago

What does an atomic number represent in an atom? 1. Number of protons 2. Number of electrons. 3. Number of neutrons. 4. Number o

WINSTONCH [101]

4: The mass amount of protons and neutrons in an atom

We just covered this in my chem class

5 0

4 years ago

Read 2 more answers

When metal atoms combine chemically with atoms of other elements, what do they usually do?

Fiesta28 [93]

Answer:

Maybe I know too much chemistry but how the metals (and the non-metals) react depends on where they are in the Periodic Table. The metals in groups I and II over on the far left side are explosively reactive and loose electrons and form ionic bonds. Examples: Na+1 has lost 1 electron and Li+2 has lost 2 electrons. The metals in the higher groups are more confusing but most of them share outer shell electrons and form covalent bonds. Examples: Fe2O3 (rust) where Iron shares 2X3 electrons with Oxygen which shares 3X2 electrons. Confused enough? :-)

The answer you'll be expected to give depends on the subject of the chapter you're studying. If you're studying covalent bonds, then the answer will probably be "form covalent bonds". If you're studying ionic bonds, then the answer will be "lose electrons".

Explanation:

This may not be the answer... I'm sorry if it's not

8 0

3 years ago

How many moles of gaseous boron trifluoride, BF3, are contained in a 4.3410 L bulb at 788.0 K if the pressure is 1.220 atm What

gregori [183]

Answer:

n= 0.08186

{He}2s^2 2p^6

Explanation:

PV=nRT

n=PV/RT

n= (1.220 atm)(4.3410 L) / (0.0821 atm*L/mol*K)(788.0 K)

n=0.08186

As for the electron configuration:

Ne:

{He} 2s^2 2p^6

or long hang:

1s^2 2s^2 2p^6

5 0

3 years ago

The unit cell for cr2o3 has hexagonal symmetry with lattice parameters a = 0.4961 nm and c = 1.360 nm. If the density of this ma

IRINA_888 [86]

To calculate the packing factor, first calculate the area and volume of unit cell.

Area is calculated as:

$A=6R^{2}\sqrt{3}$

Here, R is radius and is related to a as follows:

$R=\frac{a}{2}$

Putting the value in expression for area,

$A=6(\frac{a}{2})^{2}\sqrt{3}=1.5a^{2}\sqrt{3}$

The value of a is 0.4961 nm

Since, $1 nm=10^{-7}cm$

Thus, $0.4961 nm=4.961\times 10^{-8} cm$

Putting the value,

$Area=1.5(4.961\times 10^{-8}cm)^{2}\sqrt{3}=6.39\times 10^{-15}cm^{2}$

Now, volume can be calculated as follows:

$V=Area\times c$

The value of c is 1.360 nm or $1.360\times 10^{-7} cm$

Putting the value,

$V=(6.39\times 10^{-15}cm^{2})\times (1.360\times 10^{-7} cm)=8.7\times 10^{-22}cm^{3}$

now, number of atom in unit cell can be calculated by using the following formula:

$n=\frac{\rho N_{A}V_{c}}{A}$

Here, A is atomic mass of $Cr_{2}O_{3}$ is 151.99 g/mol.

Putting all the values,

$n=\frac{(5.22 g/cm^{3})(6.023\times 10^{23} mol^{-1})(8.7\times 10^{-22}cm^{3})}{(151.99 g/mol)}\approx 18$

Thus, there will be 18 $Cr_{2}O_{3}$ units in 1 unit cell.

Since, there are 2 Cr atoms and 3 oxygen atoms thus, units of chromium and oxygen will be 2×18=36 and 3×18=54 respectively.

The atomic radii of $Cr^{3+}$ and $O^{2-}$ is 62 pm and 140 pm respectively.

Converting them into cm:

$1 pm=10^{-10}cm$

Thus,

$r_{Cr^{3+}}=6.2\times 10^{-9}cm$

and,

$r_{O^{2-}}=1.4\times 10^{-8}cm$

Volume of sphere will be sum of volume of total number of cations and anions thus,

$V_{S}=V_{Cr^{3+}}+V_{O^{2-}}$

Since, volume of sphere is $V=\frac{4}{3}\pi r^{3}$ ,

$V_{S}=36\left ( \frac{4}{3}\pi (r_{Cr^{3+})^{3}} \right )+54\left ( \frac{4}{3}\pi (r_{O^{2-})^{3}} \right )$

Putting the values,

$V_{S}=36\left ( \frac{4}{3}(3.14) (6.2\times 10^{-9} cm)^{3}} \right )+54\left ( \frac{4}{3}(3.14) (1.4\times 10^{-8} cm)^{3}} \right )=6.6\times 10^{-22}\times 10^{-8}cm^{3}$

The atomic packing factor is ratio of volume of sphere and volume of crystal, thus,

$packing factor=\frac{V_{S}}{V_{C}}=\frac{6.6\times 10^{-22}cm^{3}}{8.7\times 10^{-22}cm^{3}}=0.758$

Thus, atomic packing factor is 0.758.

6 0

3 years ago

Read 2 more answers