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开始学习
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Tiny particles that make up all elements and substances
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What is the structure of an atom? 开始学习
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A central nucleus containing protons and neutrons, surrounded by electrons in shells
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Which particles are found in the nucleus? 开始学习
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Where are electrons found? 开始学习
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In the shells around the nucleus
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What is the relative mass of a proton & neutron? 开始学习
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What is the relative mass of an electron? 开始学习
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开始学习
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Because the number of protons equals the number of electrons
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开始学习
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A charged particle formed when an atom gains or loses electrons
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What happens when an atom loses electrons? 开始学习
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It becomes a positive ion
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What happens when an atom gains electrons? 开始学习
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It becomes a negative ion
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What is the atomic number? 开始学习
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The number of protons in an atom
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What does the atomic number tell you? 开始学习
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开始学习
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The total number of protons and neutrons
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How do you calculate neutrons 开始学习
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Number of neutrons = mass number - atomic number
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开始学习
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Atoms of the same element with the same number of protons but a different number of neutrons
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Why do isotopes have different masses? 开始学习
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Because they contain different numbers of neutrons
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Why do isotopes react the same chemically? 开始学习
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Because they have the same number of electrons
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What is relative atomic mass? 开始学习
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The average mass of all the isotopes of an element
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How is relative atomic mass calculated? 开始学习
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Sum of (isotope abundance x isotope mass) / total abundance
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What is an electron configuration? 开始学习
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The arrangement of electrons in shells around the nucleus
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Why are full outer shells important? 开始学习
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Atoms are more stable when their outer shell is full
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Why are noble gases unreactive? 开始学习
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They already have full outer electron shells
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What ion does sodium form? 开始学习
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Na+ because it loses 1 electron
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What ion does fluorine form? 开始学习
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F- because it gains 1 electron
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What ion does calcium form? 开始学习
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Ca2+ because it loses 2 electrons
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