Protons and neutrons have similar mass. Electrons are smaller than a proton or a neutron. An atomic scientist was studying an atom and through experimentation found that the total negative charge of the area surrounding the nucleus is -9.
Answer:
period 6
Explanation:
If the lanthanides were inserted into the periodic table, they would go into periodic 6.
Their atomic number is between 57 - 71 from element lanthanum to lutetium.
- The elements in this period are 15 in number.
- They are also know as elements in the f-block.
The elements that makes up the series are:
Lanthanum
Cerium
Praseodymium
Neodymium
Promethium
Samarium
Europium
Gadolinium
Terbium
Dysprosium
Holmium
Erbium
Thulium
Ytterbium
Lutetium
Gravitational <span>force between them</span>
