To determine the total number of elements in a chemical formula, you need to follow these steps:
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Identify the Elements: Chemical formulas consist of symbols representing different elements. For example, in the formula \( H_2O \), the elements present are Hydrogen (H) and Oxygen (O).
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Count Unique Elements: Count each unique element that appears in the formula. In \( H_2O \), there are two different elements: H and O.
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Subscripts: Pay attention to subscripts (the small numbers that appear to the lower right of an element symbol). These indicate the number of atoms of that element in the compound. For example, in \( C_6H_{12}O_6 \) (glucose), there are:
- 6 Carbon atoms (C)
- 12 Hydrogen atoms (H)
- 6 Oxygen atoms (O) Despite the numbers, you only count unique elements: C, H, and O. So, there are 3 unique elements here.
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No Subscript Means One Atom: If there is no subscript after an element's symbol, it means there is just one atom of that element in the formula. For example, in \( NaCl \) (sodium chloride), there is one Na (sodium) and one Cl (chlorine), making a total of 2 unique elements.
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Final Count: Add up the total number of unique elements.
For example:
- In \( Ca(NO_3)_2 \):
- The elements are Calcium (Ca), Nitrogen (N), and Oxygen (O).
- Total unique elements = 3 (Ca, N, O).
In summary, to determine the total number of elements in a chemical formula, identify each unique element represented and count them, regardless of the number of atoms indicated by subscripts.