Question

key concept summary

• chemical compounds are formed from elements in the periodic table.
• chemical compounds are represented using chemical names and chemical formulas.
• reactive elements can become more stable when they form compounds.
• chemical compounds are described as either ionic or molecular.
• ionic compounds are named with the metal ion first, and then the non - metal ion ending in \ide.\
• molecular compounds are named using numerical prefixes.

1. a) provide the name and symbol for a metallic element.

b) which group of non - metals is the most reactive? why?
c) which metal is the most reactive? why?

1. write the chemical formula for each of the following compounds given the number of each type of element present:

a) 2 atoms nitrogen, 2 atoms hydrogen
b) 1 atom calcium, 1 atom carbon, 3 atoms oxygen
c) 3 atoms calcium, 2 atoms phosphorus
d) 2 atoms sodium, 2 atoms sulfur, 3 atoms oxygen

Explanation:

Step1: Answer 2a

Choose a common metallic element.
Iron, symbol Fe

Step2: Answer 2b

The halogens (Group 17) are most reactive non - metals.
They need one electron to complete their outer shell.

Step3: Answer 2c

Cesium (or Francium, but Francium is rare) is a very reactive metal.
It has a large atomic radius and easily loses its outer electron.

Step4: Answer 3a

Write the chemical formula based on atom numbers.
$N_2H_2$

Step5: Answer 3b

Write the formula for the compound with given atoms.
$CaCO_3$

Step6: Answer 3c

Write the formula for the calcium - phosphorus compound.
$Ca_3P_2$

Step7: Answer 3d

Write the formula for the sodium - sulfur - oxygen compound.
$Na_2S_2O_3$

Answer:

2a. Iron, Fe
2b. Group 17 (halogens), because they need one electron to complete their outer shell.
2c. Cesium (or Francium), because it has a large atomic radius and easily loses its outer electron.
3a. $N_2H_2$
3b. $CaCO_3$
3c. $Ca_3P_2$
3d. $Na_2S_2O_3$