It's a physical change because the composition of the salt hasn't change. Only the change in substance/form has occured. To tell if something has undergone physical change is:
• Melting
• Boiling
• Freezing
• Condensing
• Breaking
• Bending
• Dissolving
• Molecules can change motion and proximity
To tell if something changed chemically:
• Molecules rearrange with other molecules to make new substance
• Can be production of flames
• Color change
• Bubbling/fizzing
• Temp. change
• change in composition
sodium chloride is a compound that is stable because its constituent elements namely chlorine and sodium have formed ionic bonds with each other and their outer energy shells are filled with 8 electrons.
Sodium on its own has 11 electrons. Two of these are in the 1st energy level, eight in the 2nd energy level and one in the 3rd energy level. This arrangement is highly unstable rendering the element sodium highly unstable and reactive. It will burst into flames immediately on exposure to air and can burn through human flesh if it comes into contact with it.
Chlorine at room temperature is a poisonous gas. It has 17 electrons in the arrangement 2:8:7 . The outermost shell has 7 electrons and so this element is fairly stable but will readily react with human lungs with fatal consequences.
So each of these two elements on their own are deadly, but when the two react together, sodium gives up its single electron on the outer energy shell to chlorine which readily accepts it and fills its outer shell to make 8 forming ionic bonds and is thus the two are completely stable and cannot explode or react in any other way because the outer shell of each of them is now filled with 8 electrons.
Answer:
Explanation:
R = Rydberg constant = 
= Principal quantum number of an energy level = 2
= Principal quantum number of an energy level for the atomic electron transition = 4
Wavelength is given by the Rydberg formula
The wavelength of the light emitted is .
Iron-55 (55Fe) is a radioactive isotope of iron with a nucleus containing 26 protons and 29 neutrons.
Answer:
Substance with a nonpolar covalent bonds is 
.
Explanation:
Polar covalent compound: This compound is formed when difference in electronegativity between the atoms is present. When atoms of different elements combine, it results in the formation of polar covalent bond. For Example: 
etc..
Non-polar covalent compound: This compound is formed when there is no difference in electronegativity between the atoms. When atoms of the same element combine, it results in the formation of non-polar covalent bond. For Example: 
etc.
Substance with a nonpolar covalent bonds is .
