Question

period: 12 seat #: 21
chemistry 1: first semester final assessment
alloted period of time 1 hour and 40 min.
directions: fill in missing words, determine what coefficients and subscripts are needed, create proper diagrams, always list the electron configurations when they are needed, show your math on the back of the assessment sheet, use this area for calculating the balancing tools for balancing equations placing the final answer on the front of the page.

1. explain what is meant by the term isotope.

1. an atom has an atomic number of 24, what is its atomic mass?

how many protons and neutrons
does this atom have?

draw a circular (orbital) example of what this atom would look like:

1. 4 points: give two examples of each - alkaline metal atoms, halogen atoms, transition metals, and metalloids:

alkaline metal	halogen	transition metal	metalloids

1. in what direction in a period of the periodic table of elements does the electronegativity increase?

Explanation:

Question 1

Isotopes are atoms of the same element (same atomic number, so same number of protons) that have different numbers of neutrons, resulting in different atomic masses. For example, carbon - 12 and carbon - 14 are isotopes of carbon; both have 6 protons, but carbon - 12 has 6 neutrons and carbon - 14 has 8 neutrons.

Step 1: Determine the element and protons

The atomic number is equal to the number of protons. Given the atomic number is 24, the element is chromium (Cr). The number of protons is equal to the atomic number, so protons = 24.

Step 2: Calculate atomic mass and neutrons

The atomic mass of an atom is approximately the sum of protons and neutrons. For chromium, the most common isotope has a mass number (atomic mass) of 52 (since protons + neutrons≈atomic mass). To find neutrons, use the formula: neutrons = atomic mass - atomic number. So neutrons = 52 - 24 = 28.

Step 3: Orbital diagram description

The electron configuration of chromium (atomic number 24) is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{5}$ (it has a special configuration due to the stability of half - filled d - orbitals). The orbital diagram would have: 1s orbital with 2 electrons, 2s with 2, 2p with 6, 3s with 2, 3p with 6, 4s with 1, and 3d with 5 electrons. The nucleus (containing 24 protons and 28 neutrons) is at the center, and the electrons are in their respective orbitals around the nucleus.

• Alkaline Metals: These are in Group 1 of the periodic table (excluding hydrogen). Examples include Lithium (Li) and Sodium (Na).
• Halogens: These are in Group 17 of the periodic table. Examples include Fluorine (F) and Chlorine (Cl).
• Transition Metals: These are in the d - block of the periodic table (Groups 3 - 12). Examples include Iron (Fe) and Copper (Cu).
• Metalloids: These have properties between metals and non - metals. Examples include Silicon (Si) and Germanium (Ge).

Answer:

Atoms of the same element (same atomic number) with different neutron numbers (and thus different atomic masses).

Question 2