Page 25 - PRE-U STPM CHEMISTRY TERM 1

Chemistry Term 1 STPM
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In the formation of Al , the electron removed is from the 3p orbital:
2
2
2
6
The configuration of Al is 2.8.2 or 1s 2s 2p 3s .
+

3 In the formation of anions, electrons are added in the same CHAPTER
manner as filling of electrons. 2

5
4 The electronic configuration of fluorine is 2.7 or 1s 2s 2p .
2
2
1s 2s 2p

The additional electron is added to one of the 2p orbitals which
have only one electron.
1s 2s 2p

2
2
–
6
The electronic configuration of F is 2.8 or 1s 2s 2p .
Quick Check 2.4

1 Write the electronic configurations for the following atoms:
(a) Ge (c) Pb
32 82
(b) Br
35
2 Iron (proton number 26) is a d block element. It can form two stable ions, Fe and Fe .
3+
2+
Write the electronic configuration for:
(a) the iron atom, and
(b) the Fe and Fe ions.
2+
3+
(c) Based on the electronic configuration in (b), state and explain which oxidation state of iron is
more stable?

2.4 Classification of Elements in 2017/P1/Q3

the Periodic Table 2018/P1/Q3

1 In the modern Periodic Table, the elements are arranged in order of
increasing proton numbers.
2 In 1984, the International Union of Pure and Applied Chemistry
(IUPAC) formally recommended the format as shown:

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02 Chapter 2.indd 55 3/26/18 3:14 PM