Page 14 - PRE-U STPM CHEMISTRY TERM 1

Chemistry Term 1 STPM

Quick Check 2.2

1 The difference in energy between two levels in the hydrogen atom is 3.03  10 J.
–19
(a) Calculate the frequency of light emitted when transition takes place between these two levels.
CHAPTER 2 The line spectrum of sodium consists of a line with wavelength of 590 nm.
(b) In what part of the electromagnetic spectrum is the light emitted?
2 (a) Calculate its frequency.

–1
(b) Calculate the difference in energy (in kJ mol ) between the two levels where the
transition occurs.
3 The energies of the orbits in the hydrogen atom are as shown below:

1277 n = 6
1261 n = 5
1231 n = 4
y
1168 n = 3
985 n = 2

x
0 n = 1

Calculate the frequencies of the lines marked x and y.

Ionisation Energy of Hydrogen
2013/P1/Q18(b)
Definition of the ionisation energy 1 Ionisation energy of hydrogen is the minimum energy required to
remove the lone electron in the hydrogen atom per mole of gaseous
of hydrogen
hydrogen atom under standard conditions (298 K and 101 kPa).
+
H(g) → H (g) + e
2 For the hydrogen atom, the ionisation energy corresponds to the
difference in energy between the levels, n = 1 and n = ∞.

n = ∞

∆E = ionisation energy

n = 1

The line with maximum 3 The electronic transition between these two levels will result in a
frequency is known as line with maximum frequency in the Lyman series of the hydrogen
the convergence limit or
convergence frequency. line spectrum.

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02 Chapter 2.indd 44 3/26/18 3:14 PM