Answer:
Mass = 20 g
Explanation:
Given data:
Number of moles of He = 5 mol
Mass of He = ?
Solution:
Formula:
Number of moles = mass/ molar mass
Molar mass = 4 g/mol
by putting values,
5 mol = Mass / 4 g/mol
Mass = 5 mol × 4 g/mol
Mass = 20 g
Before the periodic table, there were a bunch of symbols, number, letters etc (In all kinds of languages) that represented the elements. Scientists around the world saw that a chart of the elements needed to be universally accepted and finalized. A guy named Mendeleev presented this idea to the scientific community. Mendeleev was also the first to order elements according to atomic number rather than atomic weight. The modern day periodic table was not published by him, it was developed with the help of the entire scientific community. Honestly, there isn't a specific way to tell you how the periodic table was constructed, scientists developed thousands of tables that represented the elements. And just to let you know, the modern day periodic table is constantly going through changes as we discover more and more about elements, atoms, molecules etc. so in the near future it wouldn't be surprising if we saw something completely different than what we see today.
Answer:
Δm = 3.0684
Explanation:
Data Given:
Atomic number of lithium = 3
Atomic mass of lithium = 7.0144 amu
Mass of 1 proton = 1.0073 amu
Mass of 1 neutron = 1.0087 amu
Solution:
Mass Defect:
Mass defect is the difference of mass number of an atom and its atomic number.
Formula used
Δm = [Z (mass of proton + mass of nutron) + ( A − Z ) mass of nutron] − m of atom
where:
Δm = mass defect (amu)
Z = atomic number
A = mass number
Put values in formula
Δm = [3 ( 1.0073 amu + 1.0087 amu) + ( 7 − 3 ) 1.0087 ] − 7.0144
Δm = [3 (2.016) + (4) 1.0087 ] − 7.0144
Δm = [(6.048) + (4.0348) ] − 7.0144
Δm = 10.0828 − 7.0144
Δm = 3.0684
B. Amount of sunlight received
Answer:
<em>cohesive forces between liquid molecules </em>
Explanation:
The cohesive forces between molecules down into a liquid are shared with all neighboring atoms. Those on the surface have no neighboring atoms above, and exhibit stronger attractive forces upon their nearest neighbors on the surface.
