What is the identity of element X if the ion X* contains 18 electrons and 19 protons? O K Ca Mg Na

2. Which of the following is closest to the observed abundance of 71Ga, one of two stable gallium isotopes (69Ga and 71Ga)? 20% 60% 70% 40%

2-99 A 7.12 g sample of magnesium is heated with 1.80 g of bromine. All the bromine is used up, and 2.07 g of magnesium bromide is produced. What mass of magnesium remains unreacted?

What is the charge on the common monatomic ions of the following elements? (a) selenium (b) fluorine (c) iron (d) nitrogen

One isotope of a metallic element has mass number 74 and has 51 neutrons in the nucleus. An atomic ion has 18 electrons. Write the symbol for this ion (give the symbol for the nucleus and give the ionic charge as a right superscript).

1. Which is the more abundant isotope of copper, 63Cu or 65Cu? 63Cu 65Cu

2-103 The element silver has two naturally occurring isotopes: 109Ag and 107Ag with a mass of 106.905 amu. Silver consists of 51.82% 07Ag and has an average atomic mass of 107.868 amu. Calculate the mass of 109Ag

A sample of green crystals of nickel(II) sulfate heptahydrate was heated carefully to produce the bluish green nickel(II) sulfate hexahydrate. What are the formulas of the hydrates? If 8.753 g of the heptahydrate produces 8.192 g of the hexahydrate, how many grams of anhydrous nickel(II) sulfate could be obtained?

2-59 You are presented with a Lewis dot structure of element X as X.. To which two groups in the Periodic Table might this element belong?

Myocardial perfusion imaging (MPI) is the latest tool used in the detection of coronary artery disease. It uses thallium-201 chloride. How many neutrons are in (a) seventy atoms of thallium-201 ? (b) one picogram (11012g) of thallium-201?