What is the effect of size along the period?
What is the effect of size along the period?
Experiments have shown that the first case is what happens: the increase in nuclear charge overcomes the repulsion between the additional electrons in the valence level. Therefore, the size of atoms decreases as one moves across a period from left to right in the periodic table.
How does atomic size vary along the period give reason?
Atomic size is the distance between the center of nucleus and the outermost electron in the outer shell. Across a period from left to right there is decrease in atomic size with increase in nuclear charge of the element. Atomic size increases down the group because of addition of extra shell.
Why is it difficult to measure the size of an atom?
The size of an isolated atom can’t be measured because we can’t determine the location of the electrons that surround the nucleus. We can estimate the size of an atom, however, by assuming that the radius of an atom is half the distance between adjacent atoms in a solid.
How does the size of atoms vary from left to right in a period and on descending a group in the periodic table?
The atomic size increases from the top to the bottom in any group as a result of increases in all of the three factors. (As the number of energy levels increases, the size must increase.) Going across a period (from left to right), the number of protons increases and therefore the nuclear charge increases.
What affects the size of an atom?
The actual trends that are observed with atomic size have to do with three factors. These factors are: the number of protons in the nucleus (called the nuclear charge). the number of energy levels holding electrons and the number of electrons in the outer energy level.
Why is some mass missing after fission?
This huge force over a small distance leads to a fair amount of released energy which is large enough to cause a measurable reduction in mass. This means that the total mass of each of the fission fragments is less than the mass of the starting nucleus. This missing mass is known as the mass defect.
How many unstable elements are there?
For each of the 80 stable elements, the number of the stable isotopes is given. Only 90 isotopes are expected to be perfectly stable, and an additional 162 are energetically unstable, but have never been observed to decay….Tables.
| Element | krypton |
|---|---|
| unstable in italics odd neutron number in pink | 84 Kr |
| 86 Kr | |
| 82 Kr | |
| 83 Kr |
Which has the longest half-life?
xenon-124’s