Answer: Elements in Group 2
Explanation: The periodic table was arranged by Dmitri Mendeleev specifically around similarites in their chemical behaviors. He found that as atomic number increases, at some point an element starts to react in a manner similar to a previous one. When that happened, he would place the larger element under the smaller one, and eventually noticed a periodicity in the table. Elements in a column (Groups) had similiar chemical properties. We know today that these similarities are due to the electron configuration, and that these configurations repeat themselves. He left gaps in the table when he could find an existing element with properties similar to others in that group. I big leap of faith, but it worked. Elements for those missing boxes were eventually discovered.
Answer:
it is because of Dark Matter
Dark Matter, component of the universe whose presence is discerned from its gravitational attraction rather than its luminosity. Dark matter makes up 30.1 percent of the matter-energy composition of the universe; the rest is dark energy (69.4 percent) and “ordinary” visible matter (0.5 percent).
Dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation. Dark matter is material that cannot be seen directly.
Explanation:
Hope It helps
Have A Nice Day : )
When you add heat to a solid the particles gain energy and start to vibrate faster and faster.
When you add heat to a liquid the particles are given more energy and move faster and faster expanding the liquid.
Answer:
Three hydrogen atoms to form PH₃.
Explanation:
Hello!
In this case, since the elements belonging to the nitrogen family (N, P, As, Sb and Bi) show five valence electrons, because there are five electrons at their outer shell, it is clear that if phosphorous bonds with hydrogen, it is going to require the same amount of oxygen atoms (3) because elements having five valence electrons need 3 bonds in order to attain the octet (5+3=8).
Therefore the compound would be:
Which is phosphine.
Best regards!
