The prefix "poly-" means "many," and "atomic" refers to atoms, so a polyatomic ion is made of 2+ atoms covalently bonded together. These ions are charged, which is why they can never stand alone.
It’s mass number would be 5 as it’s the protons and the neutrons added together
Answer:
the answer is O²- hopefully
The magnitude of dispersion forces in Br2 is greater than the magnitude of dispersion forces in Cl2.
Atomic radius decreases across the period but increases down the group. As more shells are added to the atom, the repulsion between electrons increases. Across the group, more electrons are added without increase in the number of shell hence atomic radius decreases across the period due to increase in the size of the nuclear charge. Therefore, the atomic radius of Li is larger than that of Be.
Ionization energy is a periodic trend that increases across the period but decreases down the group. Since the outermost electron is further from the nucleus due to screening of inner electrons, ionization energy decreases down the group. Across the period, the size of the nuclear charge increases hence ionization energy increases across the period.
For K, the second electron is removed from an inner shell which requires a very large amount of energy. In Ca, the second electron is removed from the valence shell which requires a lesser amount of energy. Therefore, the second ionization energy of K is greater than the second ionization energy of Ca.
The carbon to carbon bond in C2H4 is a double bond which has a greater bond enthalpy than the single bond in C2H6. As such, the carbon to carbon bond in C2H4 has a greater bond energy than the carbon to carbon bond in C2H6.
The boiling point of Cl2 is lower than the boiling point of Br2 because Br2 is larger than Cl2 hence the magnitude of dispersion forces in Br2 is greater than the magnitude of dispersion forces in Cl2.
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