Cancel Air Reservation. This page allows you to retrieve a Southwest Airlines reservation prior to cancelling it. Reservations purchased through Southwest Vacations, Southwest Groups, and Southwest ticket counters cannot be cancelled online.
Calcium is dull gray, but it is shiny when scratched. Other physical properties. Calcium is an excellent conductor of electricity. It is very soft and easily scratched. Chemical properties. Calcium reacts rapidly with air to form a coating of gray oxide, and it burns with a red flame.
1 Calcium is the main component of teeth and bones. 2  Calcium is the fifth most abundant element in the human body. 3  Approximately one third of the mass of the human body is calcium after all water is removed.4  Calcium burns with a dark red color in a flame test. 5  Calcium is used in fireworks to deepen the color. Calcium is the main component of teeth and bones. 2  Calcium is the fifth most abundant element in the human body. 3  Approximately one third of the mass of the human body is calcium after all water is removed.