Alkali metals: left column of your periodic table (not hydrogen, but anything below it). They have one valence electron, which they are happy to share in a reaction.
Halogens: second column from the right of your periodic table. They are one electron short of a full shell, so they are reactive in the opposite way that alkalis are--they want electrons.
Atomic number (number of protons) is the big number on the periodic table square. Hydrogen's is 1.
Atomic mass is a little number down below. For example, Hydrogen's is 1.008.
Neutrons are a tricky subject, because different isotopes of the same element can have different numbers of neutrons. You can't generally get this from the atomic mass, because the atomic mass is a weighted average of naturally occurring isotopes. Hydrogen can have 0,1, or 2 neutrons. To answer this, you'd have to choose a particular isotope from the table of isotopes (a completely different chart from the periodic table) which has a certain number of neutrons: n = weight - Z.
Valence electrons are the electrons in the outermost shell. (The column of the table).
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Number of principal shells is the row of the periodic table. </span>
Answer:
a.52.9 km/h
b.90 km
Explanation:
We are given that






Time spend on eating lunch and buying ga=15 min.
a.Total time=30+12+45+15=102 minute=
1 hour=60 minutes
Distance=



Total distance=
Average speed=
Using the formula
Average speed=
b.Total distance between the initial and final city lies along the route=90 km
The pyrite will be bigger, because its density is much lower.
I <em>do</em> know that the gold's volume will be 2.5906 (With a bunch more numbers after it)
50 divided by 19.3 = 2.5906
Dark energy is a theoretical repulsive energy that causes the acceleration to the expansion of the universe. Among the choices, the nearest answer would be D. Dark energy can also be defined as a new form of energy, that is a dynamic field that fills up space but has an effect opposite to that of normal energy.
Answer:
The acceleration is 6 [m/s^2]
Explanation:
We can find the acceleration of the roller coaster using the kinematic equation for uniformly accelerated motion.
![v_{f} =v_{i} + a*t\\where:\\v_{f} = final velocity = 22 [m/s]\\v_{i} = initial velocity = 4 [m/s]\\t = time = 3 [s]\\](https://tex.z-dn.net/?f=v_%7Bf%7D%20%3Dv_%7Bi%7D%20%2B%20a%2At%5C%5Cwhere%3A%5C%5Cv_%7Bf%7D%20%3D%20final%20velocity%20%3D%2022%20%5Bm%2Fs%5D%5C%5Cv_%7Bi%7D%20%3D%20initial%20velocity%20%3D%204%20%5Bm%2Fs%5D%5C%5Ct%20%3D%20time%20%3D%203%20%5Bs%5D%5C%5C)
Now replacing the values we have:
![a=\frac{v_{f} - v_{i} }{t} \\a=\frac{22 - 4 }{3}\\a = 6 [m/s^{2} ]](https://tex.z-dn.net/?f=a%3D%5Cfrac%7Bv_%7Bf%7D%20-%20v_%7Bi%7D%20%7D%7Bt%7D%20%5C%5Ca%3D%5Cfrac%7B22%20-%204%20%7D%7B3%7D%5C%5Ca%20%3D%206%20%5Bm%2Fs%5E%7B2%7D%20%5D)