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2 years ago

How to find the atomic number of an element

Chemistry

1 answer:

irinina [24]2 years ago

6 0

The little number at the top of the element

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Particals in the nucleus of an atom are its _________ and ____________.

Illusion [34]

That would be Protons and Neutrons.

6 0

3 years ago

Describe how a covalent bond can involve a sharing of the electrons, but still develop charges on the atoms

adelina 88 [10]

Answer:

Explanation:

Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms to gain more stability, which is gained by forming a full electron shell. By sharing their outermost (valence) electrons, atoms can fill up their outer electron shell and gain stability.

6 0

2 years ago

Arranges the following molecules in order of increasing dipole moment: <br> H2O, H2S, H2Te, H2Se.

erastova [34]

Explanation:

Dipole moment is defined as the measurement of the separation of two opposite electrical charges.

$H_{2}O$ is a bent shaped molecule with a dipole moment of 1.87.

$H_{2}S$ is also a bent shaped molecule with a dipole moment of 1.10.

$H_{2}Te$ is a also a bent shaped molecule and has a negligible dipole moment.

$H_{2}Se$ has a dipole moment of 0.29.

Therefore, given molecules are arranged according to their increasing dipole moment as follows.

$H_{2}Te$ < $H_{2}Se$ < $H_{2}S$ < $H_{2}O$

7 0

3 years ago

How is the number of moles of an element determined from a known mass?

goblinko [34]

the mass of 1 mole of the element is used as a conversion factor to convert grams to moles

4 0

3 years ago

The concentration of Pb²⁺ in a sample of wastewater is to be determined by using gravimetric analysis. To a 100.0-mL sample of t

svetoff [14.1K]

Answer:

0.005404 M

Explanation:

$Pb^{2+}(aq) + Na_{2}CO_{3}(aq) ---> PbCO_{3}(s) + 2Na^{+}(aq)$

Since you added an excess of sodium carbonate you warrantied that all the $Pb^{+2}$ in the sample reacted with it. So we can say that the insoluble lead (II) carbonate $PbCO_{3}$ contains all the $Pb^{+2}$ ions in the original sample.

The moles of $PbCO_{3}$ are:

$moles-of-PbCO_{3}=\frac{mass-of-PbCO_{3}}{Molecular-weight-of- PbCO_{3}}=\frac{0.1443g}{267\frac{g}{mol}}=0.00054 mol$

One mol of $Pb^{+2}$ is required to form one mol of $PbCO_{3}$ . So, the stoichiometric relationship between them is 1:1.

$Pb^{+2} +CO_{3}^{-2} - - - > PbCO_{3}$

Knowing this, 0.00054 is also the number of moles of $Pb^{+2}$ in the original sample.

So, the concentration of $Pb^{+2}$ in the original sample is:

$M = \frac{mol-of-Pb^{+2}}{volume-wastewater-(liters)}=\frac{0.00054}{0.1L}=0.005404 M$

8 0

3 years ago