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3 years ago

What ion will be formed by the selenium atom shown below when it has a stable set of valence electrons?

Chemistry

1 answer:

kirill [66]3 years ago

7 0

Answer:

Se⁻²

Explanation:

Even though the atom is not shown, we can consult the periodic table. Selenium (Se) is in group 6 and period 4, so it has 6 valence electrons. To be stable, the atom must have a noble gas configuration with 8 valence electrons, thus, selenium must gain 2 electrons.

When an atom gain electrons, it is negatively charged, because electrons have a negative charge. So, the ion formed is Se⁻².

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______ reactions generate thermal energy in a nuclear power plant as water is changed into steam

Jet001 [13]

Fission reactions generate thermal energy

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3 years ago

Read 2 more answers

A scientist wants to make a solution of tribasic sodium phosphate, Na3PO4, for a laboratory experiment. How many grams of Na3PO4

balu736 [363]

Answer:

51.53 grams .

Explanation:

Na₃PO₄ ⇄ 3Na⁺¹ + PO₄⁻³ .

1 mole 3 mole

725 mL of 1.3 M Na⁺ ions

= .725 x 1.3 moles of Na⁺ ions

= .9425 moles

3 mole of Na⁺ is formed by 1 mole of Na₃PO₄

.9425 mole of Na⁺ is formed by .9425/3 mole of Na₃PO₄

Na₃PO₄ needed = .9425/3 moles = .3142 moles

Molecular weight of Na₃PO₄ = 164

grams of Na₃PO₄ needed = .3142 x 164 = 51.53 grams .

8 0

3 years ago

PLS HELP QUICK ALOTTT OF POINTS

timofeeve [1]

Answer:

$\boxed {\boxed {\sf 0.80 \ mol\ F}}$

Explanation:

We are asked to find how many moles are in 4.8 × 10²³ fluorine atoms. We convert atoms to moles using Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance. In this case, the particles are atoms of fluorine.

We will convert using dimensional analysis and set up a ratio using Avogadro's Number.

$\frac {6.022 \times 10^{23} \ atoms \ F}{ 1 \ mol \ F}$

We are converting 4.8 × 10²³ fluorine atoms to moles, so we multiply the ratio by this number.

$4.8 \times 10^{23} \ atoms \ F *\frac {6.022 \times 10^{23} \ atoms \ F}{ 1 \ mol \ F}$

Flip the ratio so the units of atoms of fluorine cancel each other out.

$4.8 \times 10^{23} \ atoms \ F *\frac { 1 \ mol \ F}{6.022 \times 10^{23} \ atoms \ F}$

$4.8 \times 10^{23} *\frac { 1 \ mol \ F}{6.022 \times 10^{23} }$

Condense into 1 fraction.

$\frac { 4.8 \times 10^{23} }{6.022 \times 10^{23} } \ mol \ F$

Divide.

$0.7970773829 \ mol \ F$

The original measurement of atoms has 2 significant figures, so our answer must have the same. For the number we found, that is the hundredths place. The 7 in the thousandths tells us to round the 9 in the hundredths place up to a 0. Then, we also have to round the 7 in the tenths place up to an 8.

$0.80 \ mol \ F$

4.8 × 10²³ fluorine atoms are equal to <u>0.80 moles of fluorine.</u>

6 0

3 years ago

Define significant figure. Discuss the importance of using the proper number of significant figures in measurements and calculat

anastassius [24]

Explanation:

Significant figure is the measure of how accurately something can be measured. It carries meaning contributing to its measurement resolution. It is important to use proper number of significant figures to get a precise measurement. For example, if we use a meter stick then measurements like 0.874 meters, or 0.900 meters, are good because they indicate that we can measure to the nearest millimeter. Whereas a measurement like 0.8 does not tell that a meter stick can measure to the nearest millimeter.

7 0

3 years ago

I can't find the density of this question I need help

zaharov [31]

Density is Mass divided by volume.

4 0

4 years ago