How is the periodic table arranged?
संक्षिप्त उत्तर
Elements are arranged in order of increasing atomic number (the number of protons). Columns are called groups: elements in the same group have the same number of electrons in their outer shell, so they react in similar ways. Rows are called periods: the period number equals the number of electron shells. Metals are on the left, non-metals on the right.
स्टेप-बाय-स्टेप
- Atomic number increases from left to right along each period.
- Group 1 (alkali metals) have one outer electron and react vigorously with water.
- Group 7 (halogens) have seven outer electrons and become less reactive down the group.
- Group 0 (noble gases) have full outer shells and are unreactive.
- The transition metals sit in the central block.
हल किया गया उदाहरण
Sodium, element 11
- Electron arrangement: 2, 8, 1
- One outer electron, so Group 1
- Three shells, so Period 3
आम गलतियाँ
- Saying elements are ordered by atomic mass. Mendeleev used mass; the modern table uses atomic number.
- Mixing up groups (columns) and periods (rows).
- Saying Group 1 reactivity decreases down the group. It increases.
परीक्षा से पहले कमियाँ दूर करने का सबसे तेज़ तरीका है ट्यूटर के साथ वन-टू-वन क्लास। पहली क्लास मुफ़्त है।
रसायन विज्ञान ट्यूटर खोजें