Answer:
3 valence electrons
Explanation:
Because aluminum has three, that means three fluorines can bond. The make the formula AlF3, also known as aluminum trifluoride. Each of the fluorine atoms gets an electron to fill their shell, and the aluminum loses three, giving it a filled shell too (remember, aluminum has three extra electrons).
She will use the periodic table of elements to not only find out the chemical symbols of the elements written within the name, but also to check whether or not the elements are metals and or nonmetals, from this determine the ionic charges if needed for metals, and for metals that have more than one ionic charge, use a Roman numeral to represent the ionic charge that she would be using in writing the chemical formula of the compound.
Answer: 
Explanation: The given chemical reaction is:
Equilibrium constant (Kc) in general is written as:
![K_c=\frac{[products]}{[reactants]}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5Bproducts%5D%7D%7B%5Breactants%5D%7D)
Note:- Coefficients are written as their powers
So, the Kc expression for the above reaction will be:
![K_c=\frac{[NO]^2[Br_2]}{[NOBr]^2}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BNO%5D%5E2%5BBr_2%5D%7D%7B%5BNOBr%5D%5E2%7D)
Equilibrium moles are given for all of them. Let's divide the moles by given liters to get the concentrations.
![[NOBr]=\frac{0.412mol}{10.3L}](https://tex.z-dn.net/?f=%5BNOBr%5D%3D%5Cfrac%7B0.412mol%7D%7B10.3L%7D)
= 0.040 M
![[NO]=\frac{0.678mol}{10.3L}](https://tex.z-dn.net/?f=%5BNO%5D%3D%5Cfrac%7B0.678mol%7D%7B10.3L%7D)
= 0.0658 M
![[Br_2]=\frac{0.224mol}{10.3L}](https://tex.z-dn.net/?f=%5BBr_2%5D%3D%5Cfrac%7B0.224mol%7D%7B10.3L%7D)
= 0.0217 M
Plug in the values in the equilibrium expression to calculate Kc.
Compressions are regions of high pressure due to particles being close together
rarefactions are regions of low pressure due to particles being spread further apart
Longitudinal waves are often demonstrated by pushing and pulling a stretched slinky spring
