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2 years ago

What is the trend for atomic radii across the periods and down the group?

Chemistry

1 answer:

jok3333 [9.3K]2 years ago

5 0

Answer:

So, in general, atomic radius decreases across a period and increases down a group. Across a period, effective nuclear charge increases as electron shielding remains constant.

Explanation:

Moving from left to right across a period, the atomic radius decreases. The nucleus of the atom gains protons moving from left to right, increasing the positive charge of the nucleus and increasing the attractive force of the nucleus upon the electrons.

Have a happy day! <3Miss Hawaii

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Calculate ΔHrxnΔHrxn for the following reaction: 3C(s)+4H2(g)→C3H8(l)3C(s)+4H2(g)→C3H8(l) Use the following reactions and given

mihalych1998 [28]

Answer: The $\Delta H^o_{rxn}$ for the reaction is -120.9 kJ.

Explanation:

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

$3C(s)+4H_2(g)\rightarrow C_3H_8(l)$ $\Delta H^o_{rxn}=?$

The intermediate balanced chemical reaction are:

(1) $C_3H_8(l)+5O_2(g)\rightarrow 3CO_2(g)+4H_2O(g)$ $\Delta H_1=-2026.6kJ$

(2) $C(s)+O_2(g)\rightarrow CO_2(g)$ $\Delta H_2=-393.5kJ$ ( × 3)

(3) $2H_2(g)+O_2(g)\rightarrow 2H_2O(g)$ $\Delta H_2=-483.5kJ$ ( × 2)

The expression for enthalpy of the reaction follows:

$\Delta H^o_{rxn}=[1\times (-\Delta H_1)]+[3\times \Delta H_2]+[2\times \Delta H_3]$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(1\times -(-2026.6))+(3\times (-393.5))+(2\times (-483.5))]=-120.9kJ$

Hence, the $\Delta H^o_{rxn}$ for the reaction is -120.9 kJ.

8 0

3 years ago

Which particles can be stopped by human skin? ) alpha and beta particles only alpha particles alpha and gamma particles beta and

Helga [31]

Alpha and Beta particles can be stopped by our skin. Gamma particles cannot be stopped by our skin.

7 0

3 years ago

Read 2 more answers

What is the number of carbon atoms in the ring portion of the haworth structure of glucose?

Anna35 [415]

I have attached the picture ot the Haworth structure of glucose.

You can count in total 6 carbon atoms but only 5 are in the ring portion of the structure.

Therefore, the answer is 5.

8 0

3 years ago

Scientists believe that interactions between atoms depend mostly on the arrangement of the outermost electrons in each atom. Thi

vova2212 [387]

I’m pretty sure it’s in a group (column) of the period table. Hope this helps :)))

5 0

2 years ago

How many moles of O2 are needed to burn 2.56 moles of CH3OH?

lukranit [14]

Answer:

$n_{O_2}=3.84molO_2$

Explanation:

Hello!

In this case, since the combustion reaction of methanol is:

$CH_3OH+\frac{3}{2} O_2\rightarrow CO_2+2H_2O$

In such a way, since there is 1:3/2 mole ratio between methanol and oxygen, we can compute the moles of oxygen that are needed to burn 2.56 moles of methanol as shown below:

$n_{O_2}=2.56molCH_3OH*\frac{\frac{3}{2}molO_2}{1molCH_3OH} \\\\n_{O_2}=3.84molO_2$

Best regards!

6 0

2 years ago