Help!!!!<br><br> I can’t understand this question

The formula for a compound of Li+ ions and Br- ions is written LiBr. Why can’t it be written Li2Br? Why isn’t it written BrLi?

maksim [4K]

Lithium has charge of +1 and bromide has charge of - 1. So they combine to form the compound lithium bromide which is expressed as LiBr.

<h3><u>Explanation:</u></h3>

Lithium is an alkali metal placed in group 1 or periodic table. It has a valency of 1 which is achieved as lithium loses an electron to achieve a charge of +1.

Bromine is a halogen which is placed in group 17 of periodic table. It has a valency of 1 which is achieved as bromine looses an election to achieve a charge of - 1.

Lithium is the cation and bromide is the anion. So lithium is written in front and bromine following the cation. And as both of their valencies are 1, so they form the compound LiBr.

3 0

3 years ago

Hydrogen (H) and helium (He) are produced in the core of stars in a process called nuclear fusion. Over time stars begin to prod

rosijanka [135]

A C and D are all correct, Helium and Hydrogen only have a 1s orbital, and helium has 2 protons, while hydrogen has 1, and finally Hydrogen has no neutrons while helium has 2. Helium does not however have 8 valence electrons as the 1s orbital can only hold 2, meaning B is the “correct” (false) answer.

4 0

3 years ago

Which of the following is improper isotope notation? Explanation: Nineteen is potassium's atomic number

sasho [114]

Answer:

C. Potassium-19 .

Explanation:

Hello!

In this case, since isotopes are known be atoms of the same element with equal atomic number but different mass number, we can consider the case of carbon which has two natural occurring ones, carbon-12 and carbon-13 whereas carbon-12 has the greatest abundance. However, isotope notation may take two forms:

1. Symbol of the element followed by a dash indicating the mass number of the isotope, for instance: C-12, K-39, and so on.

2. Name of the element followed by a dash indicating the mass number of the isotope, for instance: Carbon-12, Potassium-39, and so on.

In such a way, the improper isotope notation is C. Potassium-19 , considering that A should be K-39 because atomic symbol of potassium is K, not k.

Best regards!

7 0

3 years ago

Consider the reaction pathway graph below.

igomit [66]

Answer:

subtract E from D

Explanation:

The graph shown the potential energy diagram of the reaction "reaction pathway".

X-axis represents the reaction progress, the transformation from the reactants to the products passing via the transition state.

Y-axis represents the potential energy of the reactants and the products and also the intermediate.

As clear from the attached image "F" represents the position of the reactants of the reaction, "B" represents the position of the intermediate/transition state and "G" represents the position of the products of the reaction.
Region "A" is the potential energy difference between the intermediate "B" and the reactants "F" which represents the activation energy of the reaction "Ea". Activation energy "Ea" can be defined as the minimum energy that the reactants should posses to initiate the reaction.
Region "C" is the potential energy difference between the reactants "F" and the products "G" which represents the enthalpy change of the reaction "ΔH".
<em>ΔH = pot. energy of the products "G" - pot. energy of the reactants "F".</em>
If "ΔH" is positive this means that the reaction is endothermic and this occurs when the potential energy of the products is greater than that of the reactants.

If "ΔH" is negative this means that the reaction is exothermic and this occurs when the potential energy of the products is smaller than that of the reactants.
In our example, It is obvious that the energy of the reactants is greater than the potential energy of the products.

So, ΔH will have a negative value which means that the reaction is exothermic reaction.
<em>Thus, the right choice is: "subtract E from D" would provide evidence to support the inference that this is an exothermic reaction.</em>

7 0

3 years ago

Read 2 more answers

How are objects charged by friction

mote1985 [20]

Answer:

When insulating materials rub against each other, they may become electrically charged . Electrons , which are negatively charged, may be 'rubbed off' one material and on to the other. The material that gains electrons becomes negatively charged

Explanation:

thank me later

4 0

3 years ago

Help!!!! I can’t understand this question