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Chemistry Chapter 3 : Topic 17
Ion Formation
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An atom of Sodium (Na) has one electron in its outermost shell. During a chemical reaction, it loses this electron. What is the most accurate explanation of what happens to the atom?
Reasoning: Loss of negatively charged electron leaves excess protons, making the atom a positively charged ion (cation).
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A chlorine atom has seven electrons in its valence shell. It reacts with another element and gains one electron. What is the result of this change?
Reasoning: Gain of electron increases negative charge, forming a chloride ion (Cl⁻), which is an anion.
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Which statement correctly explains why metal atoms usually form positive ions?
Reasoning: Metals have low ionization energy, so they lose electrons easily and form cations.
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A magnesium atom loses two electrons during ion formation. Which description is correct?
Reasoning: Loss of two electrons results in a + 2 charge, forming Mg²⁺ ion.
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Why does an atom become electrically charged when it forms an ion?
Reasoning: Ion formation involves only electron transfer, not proton or neutron change.
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Which process best describes the formation of a chloride ion (Cl⁻)?
Reasoning: Chlorine gains one electron to complete its octet and becomes negatively charged.
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A calcium atom forms Ca²⁺ ion. What must have happened?
Reasoning: Calcium loses two valence electrons to achieve stable configuration, forming Ca²⁺.
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Which of the following best defines a cation in terms of electron movement?
Reasoning: Cations are positively charged ions formed by loss of electrons.
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An atom becomes more stable after ion formation. What is the main reason?
Reasoning: Stability increases when outer shell is complete (octet or duet rule).
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Which element is most likely to form a negative ion?
Reasoning: Non-metals like chlorine gain electrons and form anions.
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During ion formation, which of the following remains unchanged?
Reasoning: Protons remain fixed in the nucleus; only electrons change.
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Why do atoms of group 1 elements easily form +1 ions?
Reasoning: Group 1 elements lose one valence electron to become stable.
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An atom of oxygen gains two electrons. What type of ion is formed?
Reasoning: Oxygen gains two electrons to complete octet, forming oxide ion O²⁻.
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Which statement correctly explains ion formation in ionic compounds?
Reasoning: Ionic bonding involves transfer of electrons, not sharing.
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Why do non-metals tend to form anions?
Reasoning: Non-metals gain electrons to achieve stable electronic configuration.
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If an atom loses two electrons and gains no protons, what is its net charge?
Reasoning: Loss of two negatively charged electrons gives + 2 charge.
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Which best explains why ions form during chemical reactions?
Reasoning: Atoms form ions to become more stable by completing outer shell.
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An atom becomes negatively charged when:
Reasoning: Gain of electrons increases negative charge.
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Which statement is TRUE about cations and anions?
Reasoning: Cations lose electrons (positive), anions gain electrons (negative).
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Which situation represents ion formation most correctly?
Reasoning: Metal (Mg) transfers electrons to non-metal (Cl), forming ions.
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