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3 years ago

What is the atomic number of beryllium

Chemistry

2 answers:

Alexandra [31]3 years ago

8 0

Answer:

4 the symbol is Be

Explanation:

hope this helped

barxatty [35]3 years ago

4 0

Answer:

the atomic number is 4.

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Consider an electron with charge âˆ’eâˆ’e and mass mmm orbiting in a circle around a hydrogen nucleus (a single proton) with cha

PtichkaEL [24]

Answer:

Explanation:

The net force on electron is electrostatic force between electron and proton in the nucleus .

Fc = $\frac{1}{4\pi\epsilon} \times \frac{e\times e}{r^2}$

This provides the centripetal force for the circular path of electron around the nucleus .

Centripetal force required = $\frac{m\times v^2}{r}$

$\frac{m\times v^2}{r}=\frac{1}{4\pi\epsilon} \times \frac{e\times e}{r^2}$

$v^2=\frac{e^2}{4\pi \epsilon m r}$

$v=(\frac{e^2}{4\pi \epsilon m r})^{\frac{1}{2} }$

5 0

2 years ago

Now select a longer period, say the fourth period, starting with the element in the 1A group. Again, go from left to right. What

Inessa [10]

Answer:

The pattern of change in the electron configuration increases from left to right across the period.

Explanation:

In the periodic table, elements having the same number of electrons in the outermost shell of their atoms are placed over one another in vertical columns. Each of the vertical columns is known as a group or family. while each of the resulting horizontal rows is known as a period or row.

There are 18 vertical columns and seven periods in the periodic table. Each period begins with an atom having a valence electron and ends with an atom having a complete outer shell structure of an inert gas.

The fourth period of the periodic table (d-block) consists of the transition elements.

The electron distribution into the energy levels of sublevels of atoms can be shown in any of the tree important electronic configuration.

Electronic configuration shows the sequence of filling electrons into the orbitals of the sublevels as guided by some principles.

The maximum number of electrons in the orbitals of sublevels are two for s-sublevel(one orbital) ; six for p-sublevel( three orbital); ten for d-sublevel ( five orbitals) and fourteen for f-sublevel( seven orbitals). This indicates that the maximum number of electrons in an orbital is two

In the Periodic table ,The sublevels with lower energies are filled up before those with higher energies. One important thing about this principle is that the sublevels do not fill up in numerical order. The pattern of filling is as follows:

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f etc.

5 0

3 years ago

PLEASE HELP DUE IN 30 MINUTES NO LINKS PLEASE

hammer [34]

Answer:

B is the correct answer

Explanation:

If this answer is correct plzz mark me as brainliest plzzzz

7 0

3 years ago

Please help with 3 and 4

mafiozo [28]

3. volume of gas because its changing because of the temperature
4. 67.6 breaths per minute
65+73+67+71+62=338/5=67.6
^because there are five terms that we added

7 0

3 years ago

Sodium hydroxide reacts with aluminum and water to produce hydrogen gas: 2 Al(s) + 2 NaOH(aq) + 6 H2O(l) → 2 NaAl(OH)4(aq) + 3 H

lianna [129]

Answer:

The mass of hydrogen gas formed is 0.205 grams

Explanation:

Step 1: Data given

Mass of 1.83 grams of Al

Mass of NaOH = 4.30 grams

Molar mass of Al = 26.98 g/mol

Molar mass of NaOH = 40 g/mol

Step 2: The balanced equation:

2 Al(s) + 2 NaOH(aq) + 6 H2O(l) → 2 NaAl(OH)4(aq) + 3 H2(g)

Step 3: Calculate moles of Al

Moles Al = mass Al / Molar mass Al

Moles Al = 1.83 grams / 26.98 g/mol

Moles Al = 0.0678 moles

Step 4: Calculate moles of NaOH

Moles NaOH = 4.30 grams / 40 g/mol

Moles NaOH = 0.1075 moles

Step 5: Calculate limiting reactant

For 2 moles of Al, we need 2 moles of NaOH

Aluminium is the limiting reactant. It will completely be consumed ( 0.0678 moles)

NaOH is in excess. There will react 0.0678 moles

There will remain 0.1075 - 0.0678 = 0.0397 moles

Step 6: Calculate moles of hydrogen

For 2 moles of Al, we need 2 moles of NaOH, to produce 3 moles of hydrogen

For 0.0678 moles of Al, there is produced 0.0678 *3/2 = 0.1017 moles of H2

Step 7: Calculate mass of H2

Mass of H2 = Moles H2 * Molar mass of H2

Mass of H2 = 0.1017 moles * 2.02 g/mol

Mass of H2 = 0.205 grams

The mass of hydrogen gas formed is 0.205 grams

6 0

3 years ago