The density of a group 2A metal is 1.55 g/cm³ and crystallizes in a cubic unit cell that has an edge length of 653 pm. When a 1.65 cm³ slab of this metal reacts with excess hydrobromic acid, the gas produced occupies a volume of 1.50 L with a pressure of 794 mmHg at 27.0°C. What is the identity of the metal?