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Question
Elements A, B and C have atomic number 17, 19 and 10 respectively.
State which one is a metal.
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Solution
Electronic configuration of element A = (2, 8, 8, 1) at atomic no. 19
∴ Element B having 1 electron in outermost orbit is a Metal.
RELATED QUESTIONS
Separate the following compounds into three categories - ionic, polar and covalent compounds; N2, NH4Cl, NH3, NO, NH4NO3, NCl3.
Element X is a metal with a valency 2; Y is a non-metal with a valency 3.
(a) Write an equation to show how Y forms as ion
(b) If Y is a diatomic gas, write an equation for the direct combination of X and Y to form a compound.
Elements X, Y, and Z have atomic numbers 6, 9 and 12 respectively. Which one forms a cation?
Name an element which does not contain neutron.
Five atoms are labeled A to E
|
Atoms |
Mass No |
Atomic No. |
|
A |
40 |
20 |
|
B |
19 |
9 |
|
C |
7 |
3 |
|
D |
16 |
8 |
|
E |
14 |
7 |
(a) Which one of these atoms:
(i) contains 7 protons
(ii) has electronic configuration 2,7
(b) Write down the formula in the compound formed between C and D
(c) Predict : (i) metals (ii) non-metals
Complete the following table relating to the atomic structure of some elements.
|
Element Symbol |
Atomic Number |
Mass Number |
Numbers of neutrons |
Number of Electrons |
Number of Protons |
|
Li |
3 |
6 |
|
|
|
|
Cl |
17 |
|
20 |
|
|
|
Na |
|
|
12 |
|
11 |
|
Al |
|
27 |
|
|
13 |
|
S |
|
32 |
16 |
|
|
State the type of bond between Y and Z and give its molecular formula.
In the formation of magnesium chloride (by direct combination between magnesium and chlorine), name the substance that is oxidized and the substance that is reduced.
Complete the table give below.
| Element |
Atomic number |
Electron distribution | Valence electrons | Lewis dot structure |
| Lithium | 3 | 1s22s1 | ||
| Boron | 5 | 1s22s22p1 | ||
| Oxygen | 8 | 1s22s22p4 |
The valency of noble gases is ______.
