Periodic positions follow proton number and electron structure
導入済み| English | 意味 |
|---|---|
| group/ɡruːp/ | 族 |
| period/ˈpɪərɪəd/ | 周期 |
What would explain this observation?
- Lithium and sodium are separated by several elements in proton-number order but sit in the same column. Their shared outer-electron pattern explains why their reactions resemble one another.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- The modern periodic table arranges elements by increasing atomic number. A group 族 is a column containing elements with similar chemical properties; a period 周期 is a row. For the main-group first twenty elements, occupied shells give the period, while outer electrons explain group similarities. Magnesium, 2,8,2, is in period 3 and Group 2; chlorine, 2,8,7, is in period 3 and Group 7. AQA uses Group 0 for noble gases, whose outer shell is full.
- group: A vertical column of elements with related chemical properties in the periodic table; period: A horizontal row of elements in the periodic table.
Where does the main-group atom 2,8,7 belong in AQA notation?
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The period is the number of occupied shells (3 shells: period 3) and the AQA group is the outer-electron count (7 outer electrons: Group 7). Neither is read in reverse.
Match each technical term to its precise meaning.
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Group 1 atoms tend to lose one outer electron and form +1 ions; Group 7 atoms can gain one to form −1 ions. Predict similar reaction types within a group, then use the group-specific trend for relative reactivity. Helium has two outer electrons in a full first shell and belongs with Group 0, not Group 2. Hydrogen is an unusual non-metal and should not be described as an alkali metal simply from its printed position.
- Use the supplied periodic table and numerical structures rather than memorizing an outline alone. Find Z, write the arrangement, count occupied shells, identify the outer count and compare the known group. State a prediction and the evidence for it. These main-group rules do not supply a complete electron-configuration treatment of transition metals.
Which two habits make the investigation or model in this case more defensible?
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: an unknown neutral atom has structure 2,8,8,1. Its electron total is 19, so Z=19 identifies potassium. Four occupied shells give period 4, and one outer electron gives Group 1. It is predicted to form K⁺ and to react more vigorously with water than sodium under comparable conditions, following the Group 1 trend.
How many occupied shells does a neutral atom with structure 2,8,8,1 have? Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
How many occupied shells does a neutral atom with structure 2,8,8,1 have?
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
The result is 4 shells. Known: structure 2,8,8,1. Occupied shells = 4 (the four numbers in the list). The atom is in period 4, and its single outer electron places it in Group 1.
Check the conclusion and its limits
- A group is vertical and a period horizontal. Similar properties do not mean identical reaction rates. Outer-shell count is not always the printed modern 1–18 group number, and the simplified first-twenty rule must not be applied indiscriminately to every column.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Elements in the same period must have the same outer-electron count. This claim is false: Across a period the outer shell fills from 1 to 8 electrons, so elements in the same period have every possible outer-electron count. Shared outer count defines a GROUP, not a period.
Periodic positions follow proton number and electron structure: Group 1 atoms tend to lose one outer electron and form +1 ions; Group 7 atoms can gain one to form −1 ions. Predict similar reaction types within a group, then use the group-specific trend for relative reactivity. Helium has two outer electrons in a full first shell and belongs with Group 0, not Group 2. Hydrogen is an unusual non-metal and should not be described as an alkali metal simply from its printed position.
Elements in the same period must have the same outer-electron count.
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
Across a period the outer shell fills from 1 to 8 electrons, so elements in the same period have every possible outer-electron count. Shared outer count defines a GROUP, not a period.
A vertical column of elements with related chemical properties in the periodic table: write the technical term.
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
group means A vertical column of elements with related chemical properties in the periodic table.