What is a atom of chemistry
1 answer:
Answer:
Atom is the smallest particle of matter.
Elements are made up of same atoms.
Atom consist of electron, proton and neutron.
Explanation:
Atom was first discovered by John Dalton.
word "Atom" came from Greek word, that means something that could not split. he explained that atom is indivisible particle.
In the end of 18th century J.J. Thomson put forward a new concept of atom. he said that atom have negative charged particles called electrons but overall atom is neutral.
In 1909 Rutherford with his students discovered positive charged particles and nucleus and said that it is in the center of atom.
He explain a model of atom and said that electrons revolve around a hard core in the center called nucleus.
In 1913 Niels Bohr explains the atomic spectra and put forward the concept of shells and sub-shells.
So overall Structure of an Atom is
- consist of Neutrons in nucleus
- +ve charged protons in nucleus
- A -vely charged electrons revolving around the nucleus
- the electron revolve in shells i.e. K, L, M, and N
- Each shell divide in sub-Shell such as s, p,d and f.
Atom has a specific atomic mass and atomic number
Atomic number = number of protons or electron
Atomic mass = number of protons + number of neutrons in nucleus.
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<u>Answer:</u> The freezing point of solution is -0.974°C
<u>Explanation:</u>
- To calculate the concentration of solute, we use the equation for osmotic pressure, which is:
where,
= osmotic pressure of the solution = 12.1 atm
i = Van't hoff factor = 1 (for non-electrolytes)
M = molarity of solute = ?
R = Gas constant =
T = temperature of the solution = 298 K
Putting values in above equation, we get:
This means that 0.495 moles of glucose is present in 1 L or 1000 mL of solution
- To calculate the mass of solution, we use the equation:
Density of solution = 1.034 g/mL
Volume of solution = 1000 mL
Putting values in above equation, we get:
- To calculate the number of moles, we use the equation:
Moles of glucose = 0.495 moles
Molar mass of glucose = 180.16 g/mol
Putting values in above equation, we get:
Depression in freezing point is defined as the difference in the freezing point of pure solution and freezing point of solution.
- The equation used to calculate depression in freezing point follows:
To calculate the depression in freezing point, we use the equation:
Or,
where,
Freezing point of pure solution = 0°C
i = Vant hoff factor = 1 (For non-electrolytes)
= molal freezing point elevation constant = 1.86°C/m
= Given mass of solute (glucose) = 89.18 g
= Molar mass of solute (glucose) = 180.16 g/mol
= Mass of solvent (water) = [1034 - 89.18] g = 944.82 g
Putting values in above equation, we get:
Hence, the freezing point of solution is -0.974°C