When atoms combine to form compounds, they gain, lose, or share

it depends upon the atomic number

Explanation:

if the atomic number is below 4 it will lose electrons

if the atomic number is above 4 it will gain electrons

if the atomic number is 4 it will share its electrons with other atom of the same element make covalent bonds

ex; carbon

electron

Explanation:When atoms combine to form compounds, they gain,lose,or share *electron.*

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]