AP Chemistry; Unit 1

Front

What is the ground state electron configuration of Tin (Sn)?

Back

[Kr] 4d10 5s2 5p2

Front

How do you convert grams of NaCl to moles?

Back

Use the formula: moles = mass (g) / molar mass (g/mol). For NaCl, molar mass = 58.44 g/mol. Thus, 48g NaCl = 48g / 58.44 g/mol = 0.82 mol.

Front

How does the ionic radius of a cation compare to its atomic radius?

Back

The ionic radius is smaller because the cation loses electrons, reducing electron repulsion.

Front

How do you calculate the percent composition of CaCO3 in a mixture?

Back

Percent of CaCO3 = (mass of Ca in CaCO3 / total mass of mixture) x 100. In this case, 1.5g Ca corresponds to 75% CaCO3.

Front

What is the empirical formula of a compound with 12.0g C, 3.0g H, and 8.0g O?

Back

C2H6O. Calculate moles of each element, find the simplest ratio.

Front

What is the molar mass of NaCl?

Back

Molar mass of NaCl = 22.99 g/mol (Na) + 35.45 g/mol (Cl) = 58.44 g/mol.

Front

What is the difference between atomic radius and ionic radius?

Back

Atomic radius is the size of a neutral atom, while ionic radius is the size of an ion. Cations are smaller than their parent atoms, and anions are larger.

Front

What is the significance of significant figures in calculations?

Back

Significant figures indicate the precision of a measurement. The result of a calculation should reflect the least precise measurement.

Front

How do you determine the empirical formula from mass percentages?

Back

Convert mass percentages to grams, then to moles, and find the simplest whole number ratio.

Front

What is the relationship between the number of protons and electrons in a neutral atom?

Back

In a neutral atom, the number of protons equals the number of electrons.