A compound is electrically neutral because it consists of equal numbers of positively charged ions (cations) and negatively charged ions (anions). The principle behind this neutrality lies in the balance of electrical charges:
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Ionic Compounds: In ionic compounds, atoms transfer electrons to achieve stable electron configurations, resulting in the formation of ions. For example, sodium (Na) loses one electron to become a sodium ion (Na⁺), while chlorine (Cl) gains one electron to become a chloride ion (Cl⁻). In a compound like sodium chloride (NaCl), one Na⁺ ion pairs with one Cl⁻ ion, resulting in a net charge of zero.
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Covalent Compounds: In covalent compounds, atoms share electrons instead of transferring them. This sharing leads to the formation of neutral molecules. For instance, in water (H₂O), the oxygen atom shares electrons with two hydrogen atoms. The charge distribution within the molecule is balanced, leading to overall electrical neutrality.
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Charge Conservation: The principle of charge conservation states that the total charge in a closed system remains constant. In a neutral compound, the overall positive and negative charges cancel each other out, maintaining an electrically neutral state.
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Emphasis on Structure: The arrangement of atoms in a compound typically reflects an underlying electrical balance. For ionic compounds, they arrange themselves in a lattice structure, ensuring that each positive ion is surrounded by negative ions, which furthers the balance of charges.
In summary, the electrical neutrality of a compound arises from the equal contribution of positive and negative charges, whether they be from ions in ionic compounds or from shared electrons in covalent compounds.