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:
The energy of photon, 
Explanation:
It is given that,
Voltage of anode, 
We need to find the maximum energy of the photon of the x- ray radiation. The energy required to raise an electron through one volt is called electron volt.
e is charge of electron
So, the maximum energy of the x- ray radiation is 
. Hence, this is the required solution.
Answer: • using beaker tongs to handle the hot beaker.
• checking the beaker for chips prior to heating on the hot plate.
• Turning off the hot plate after use
Explanation:
The options that will ensure laboratory safety during the experiment will be:
• using beaker tongs to handle the hot beaker.
• checking the beaker for chips prior to heating on the hot plate.
• Turning off the hot plate after use.
We should note that the beaker tongs are simply used in the holding of the beakers that have hot liquids in them. Also, it s vital for the hot plate to be turned off after its use so as to prevent accident.
Answer:
ACTION REACTION FORCES
Explanation:
When there is an action frce there will be a reaction force
