What is nitrate anion?

Write isotopic symbols of the form $X$-A (for example, C-$13$) for each isotope.

(a) the iodine isotope with $74$ neutrons

(b) the phosphorus isotope with $16$ neutrons

(c) the uranium isotope with $234$ neutrons

(d) the argon isotope with $22$ neutrons

Which element is the most electronegative among C, N, O, Br, and S? Which group does it belong to?

Among the main-group elements, what is the relationship between group number and the number of valence electrons among group members?

What is the group number and name of the group that contains potassium?

There are two naturally occurring isotopes of rubidium, Rb-85, and Rb-87. Based on the known atomic weight of rubidium, which is the most reasonable percent abundance of these two isotopes?

Calculate the equilibrium constant at 25$\degree$C for a reaction for which ∆G° = -4.22 kcal/mol.

In this reaction, does NO$_2$ $^{+}$ acts like a Lewis acid, Lewis base, Bronsted acid or Bronsted base?

A. Lewis acid
B. Lewis base
C. Bronsted acid
D. Bronsted base
E. Lewis acid and Bronsted acid

Electrical charge is sometimes reported in coulombs (C). On this scale, $1$ electron has a charge of $-1.6 \times 10^{-19} \mathrm{C}$. Suppose your body acquires $-125 \mathrm{mC}$ (millicoulombs) of charge on a dry day. How many excess electrons has it acquired? (Hint: Use the charge of an electron in coulombs as a conversion factor between charge and electrons.)

Which is a factor in determining the average atomic mass of an element?

1. atomic number of the most abundant isotope

2. relative abundance of each isotope

3. sum of atomic masses of all isotopes

4. product of atomic masses of all isotopes

5. arithmetic mean of atomic masses of the isotopes

In the text, an interpretation of the Fibonacci recursion N t + 1 = Nt + Nt−1 is given. Use a similar example to give an interpretation of the recursion N t + 1 = 2Nt + Nt−1

Take a look at the periodic table. How many elements can you find that are named after scientists you have studied?

In all, 30 chemical elements were named after people or places. Of these. 2 were named for women scientists, and 25 were named for places. What fraction of these 36 elements were named for women and places? Write your answer in simplest form.

List some examples of how elements got their names.