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solong [7]
3 years ago
12

2. From each of the following pairs of atoms, pick the atom that has

Chemistry
1 answer:
Zina [86]3 years ago
7 0

Answer:

a) Na

c) Na

b) Sr

d) Ca

Explanation:

As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As the size of atom increases the ionization energy from top to bottom also  decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.

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If this decay has a half life of 2.60 years, what mass of 72.5 g of sodium 22 will remain after 15.6 years
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Sodium-22 remain : 1.13 g

<h3>Further explanation </h3>

The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.  

Usually, radioactive elements have an unstable atomic nucleus.  

General formulas used in decay:  

\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{T/t\frac{1}{2} }}}

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\tt Nt=72.5.\dfrac{1}{2}^{15.6/2.6}\\\\Nt=72.5.\dfrac{1}{2}^6\\\\Nt=1.13~g

8 0
3 years ago
A chemist has a block of lead metal (density is 11.3 g/mL). The block weighs 2.10g. What is the volume if the lead block in mL?
mezya [45]

The volume of a block of lead metal that has a density of 11.3g/mL and weighs 2.10g is 0.186mL.

<h3>How to calculate volume?</h3>

The volume of a substance can be calculated by dividing the mass of the substance by its density. That is;

Volume = mass ÷ density

According to this question, a chemist has a block of lead metal (density is 11.3 g/mL). The block weighs 2.10g.

Volume = 2.10g ÷ 11.3g/mL

Volume = 0.186mL

Therefore, the volume of a block of lead metal that has a density of 11.3g/mL and weighs 2.10g is 0.186mL.

Learn more about volume at: brainly.com/question/18670654

#SPJ1

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1 year ago
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