Question

1. choose the best answer.

____ of an element have the same number of protons but a different number of neutrons.

ions

isotopes

nuclei

compounds

1. choose the best answer.

what law was created by johann döbereiner during early developments of the periodic table?

periodic law

law of triads

law of octaves

mendeleevs law

Explanation:

1. Isotopes are defined as atoms of the same element (same number of protons) but with different numbers of neutrons. Ions are charged atoms (due to gain or loss of electrons). Nuclei are the central part of an atom containing protons and neutrons. Compounds are substances formed from two or more elements chemically combined.
2. Johann Döbereiner created the law of triads. The periodic law is associated with Mendeleev (and others in a more refined form). The law of octaves was proposed by Newlands. Mendeleev's law is the periodic law as we know it in a more developed sense related to his periodic table.

Answer:

1. Isotopes
2. law of triads