Which of the following elements is a metal?
Atomic Number of X = 3
Atomic Number of Y = 1
Atomic Number of Z = 9
Among the given elements, element X is a metal as it can easily lose one electron to achieve the stable noble gas configuration of helium. Element X is Lithium.
Element Z will be a non-metal as it can easily accept an electron to achieve the stable noble gas configuration of neon.