# Hint 1 estimate the answer based on the percent

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Hint 1. Estimate the answer Based on the percent abundances, give an estimate of the atomic mass. ANSWER: 32.06 {\rm amu} The atomic mass will be between 69 and 70 \rm amu . equal to 69 \rm amu . between 70 and 71 \rm amu . 70.28 {\rm amu} Typesetting math: 92%
ANSWER: Correct Using the Periodic Table to Write Electron Configurations Electrons are located in a large volume of space surrounding the nucleus. This space contains different energy levels that electrons fill in order from lowest to highest in energy, and each energy level contains one or more sublevels where electrons with identical energy are found. An electron configuration is a notation used to indicate the placement of an atom's electrons in these sublevels in order of increasing energy. The configuration is written by listing the sublevels occupied by electrons from lowest to highest in energy, and by indicating how many electrons occupy each sublevel by using exponents. The sublevels, from lowest to highest in energy, are identified by the letters s , p , d , and f . Since the periodic table is arranged by the number of protons in each atom (and electrons if the atom is neutral), the sublevels form blocks in the periodic table: Energy levels depend upon what period the element resides in. If n is the period number the element resides in, 1. The energy level for s sublevels is the same as the period number ( n ). 2. The energy level for p sublevels is the same as the period number ( n ). 3. The energy level for d sublevels is one less ( n – 1) than the period number. 4. The energy level for f sublevels is two less ( n – 2) than the period number. Specific sublevels are described listing the value of the energy level followed by the type of sublevel. For example, 3 p is a p sublevel of the third energy level. Part A When writing a complete electron configuration, you write the filled sublevels in order first, and then if there is a partially filled sublevel, you write it last in the sequence. You can identify the last sublevel containing electrons by finding the element in the periodic table, and determining which block and sublevel the element corresponds to. Identify the last occupied sublevel, which can be completely or partially filled, for each of the following elements. Drag the appropriate items to their appropriate bins. Hint 1. How to approach the problem Identifying the last occupied sublevel (filled or partially filled) of an element involves two steps: 1. Locate which block the element resides in on the periodic table ( s , p , d , or f ). 2. Identify which period, or row, of the periodic table the element resides in (1­7). If n is the period number the element resides in, 1. The energy level for s sublevels is the same as the period number ( n ). 2. The energy level for p sublevels is the same as the period number ( n ). 3. The energy level for d sublevels is one less ( n – 1) than the period number. 4. The energy level for f sublevels is two less ( n – 2) than the period number. For example, yttrium ( \rm Y ) resides in the fifth period and in the d