Glossary term: 原子
Description: 原子是構成任何化學元素的最小基本單元。例如，氦氣由許多氦原子組成，每個氦原子彼此無異；碳元素（如鑽石形式）則是碳原子的集合。
“原子”一詞源於古希臘哲學家德謨克利特，他認為原子是不可分割的物質基本組成部分。然而，根據現代定義，原子由電子、質子和中子構成。質子和中子構成原子核，所有給定化學元素的原子都具有相同數量的質子，是該元素的唯一特性。原子核被電子包圍。通常所說的原子是電中性的，質子帶有單位正電荷，電子帶有單位負電荷，兩者數量相等。當電子從中性原子中被移除或被添加到中性原子時，原子則會變為離子。
電子層決定了原子的化學性質。不同種類原子的差異和相似性在元素週期表中被系統地組織和分類。電子層也決定了原子與輻射相互作用的方式。通過分析接收到的來自天體的光譜特徵，天文學家可以區分太空中存在的不同種類原子。
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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
This is an automated transliteration of the simplified Chinese translation of this term
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