Transition metals form ions with incomplete d orbitals.
Thallium is in the group 5 and lead in the group 6 of the periodic table.
FOR THE SIZEthe elements on the periodic tabledecreases across the periodand increases down the groupFOR THE ELECTRON DIFFERENCEFor the first 20 elementacross the period the difference between two closes element is +1 eletron or -1 eletrondown the group the difference between two closes element is +8 eletron or -8 eletron
families determine the energy level of an element and groups determine their properties.
Sodium is an element on the periodic table, sodium hydroxide is a compound of sodium (Na) and hydrogen and oxygen (OH)
Ruthenium.
Ru
biology
Radium (Ra) # 88th element in the periodic table.
In scientific terms, an element is anything that can be found on the Periodic Table of Elements (PTE). It is a pure substance, not mixed with anything else. Compounds are a combination of 2 or more elements. They cannot be found on the PTE.
a compound is more then one element
All isotopes of an element have the same number of protons in the atomic nucleus, which is its atomic number on the periodic table. All isotopes of an element contain different numbers of neutrons in their atomic nuclei, which causes the isotopes of an element to vary in mass number (protons + neutrons).