Mendeleev used his arrangement of elements in order of increasing mass and repeated properties to predict the mass and properties of undiscovered elements. true or false

True.

Elements are arranged by Mendeleev according to increasing mass in rows to put the elements with similar properties in the same column. Due to undiscovered elements, he was unable to make the complete table, but he left some gaps to put the new elements after their discoveries. In this way, properties of new elements can be identified by arranging the elements in increasing order of mass and repeated properties.

Therefore, the statement "Mendeleev used his arrangement of elements in order of increasing mass and repeated properties to predict the mass and properties of undiscovered elements" is true.

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.