Answer:
Helium
Explanation:
Atomic radii vary in a predictable manner across the periodic table. As can be seen in the figures below, the atomic radius increases from top to bottom in a group and decreases from left to right over a period of time. Helium is therefore the smallest element, and francium is the largest.
Atoms are electrically neutral because they have equal numbers of protons (positively charged) and electrons (negatively charged).
Answer:
139/56 Ba
Explanation:
In writing nuclear equations, there must be a balance of the mass and charge on both sides of the reaction equation. That is, the sum of masses on the lefthand side of the nuclear reaction equation must equal the sum of masses on the righthand side of the nuclear reaction equation. Similarly, the charges on the lefthand side of the nuclear reaction equation must equal the sum of the charges on the right hand side of the nuclear reaction equation.
Hence, the isotope of barium formed in the equation mentioned in the question is 139/56 Ba.
