Periods
Characteristics of periods The first period starts with hydrogen (H) and ends with helium (He). It has just two elements H (Z=1) and He (Z = 2). H has one… Read More »Periods
Characteristics of periods The first period starts with hydrogen (H) and ends with helium (He). It has just two elements H (Z=1) and He (Z = 2). H has one… Read More »Periods