When we look at the periodic table, we can see that the elements in Group 1 (called alkali metals) and Group 17 (known as halogens) act very differently when they react.
So, why do they behave this way?
It all comes down to how their electrons are arranged. Each element wants to feel stable, just like noble gases, which are the most stable group.
Electron Arrangement: These elements have one electron in their outer layer. For example, lithium has the arrangement that looks like this: 1s² 2s¹.
How They React: They are very reactive because they want to get rid of that one electron to feel stable. For example, sodium (Na) reacts quickly with water. This creates sodium hydroxide (NaOH) and hydrogen gas (H₂). You can write it like this:
2 Na + 2 H₂O → 2 NaOH + H₂
Trend: As we move down the group from lithium to cesium, they get more reactive. This is because the outer electron is farther from the center of the atom, making it easier to lose.
Electron Arrangement: These elements have seven electrons in their outer layer. For instance, chlorine has an arrangement like this: [Ne] 3s² 3p⁵.
How They React: They are also reactive, but for a different reason. They want to gain one more electron to fill up their outer layer. For example, chlorine (Cl) easily reacts with sodium (Na) to make table salt (sodium chloride). This reaction can be shown as:
Na + Cl₂ → 2 NaCl
Trend: As we go down the group from fluorine to iodine, they become less reactive. This is because larger atoms find it harder to pull in an extra electron since it’s farther away from the center.
To wrap it up, Group 1 elements lose one electron to feel stable, while Group 17 elements gain one electron. This basic difference in how they handle electrons explains why they react in such different ways and shows us their patterns on the periodic table.
When we look at the periodic table, we can see that the elements in Group 1 (called alkali metals) and Group 17 (known as halogens) act very differently when they react.
So, why do they behave this way?
It all comes down to how their electrons are arranged. Each element wants to feel stable, just like noble gases, which are the most stable group.
Electron Arrangement: These elements have one electron in their outer layer. For example, lithium has the arrangement that looks like this: 1s² 2s¹.
How They React: They are very reactive because they want to get rid of that one electron to feel stable. For example, sodium (Na) reacts quickly with water. This creates sodium hydroxide (NaOH) and hydrogen gas (H₂). You can write it like this:
2 Na + 2 H₂O → 2 NaOH + H₂
Trend: As we move down the group from lithium to cesium, they get more reactive. This is because the outer electron is farther from the center of the atom, making it easier to lose.
Electron Arrangement: These elements have seven electrons in their outer layer. For instance, chlorine has an arrangement like this: [Ne] 3s² 3p⁵.
How They React: They are also reactive, but for a different reason. They want to gain one more electron to fill up their outer layer. For example, chlorine (Cl) easily reacts with sodium (Na) to make table salt (sodium chloride). This reaction can be shown as:
Na + Cl₂ → 2 NaCl
Trend: As we go down the group from fluorine to iodine, they become less reactive. This is because larger atoms find it harder to pull in an extra electron since it’s farther away from the center.
To wrap it up, Group 1 elements lose one electron to feel stable, while Group 17 elements gain one electron. This basic difference in how they handle electrons explains why they react in such different ways and shows us their patterns on the periodic table.