Down a group,
the number of energy levels (n) increases
, so there is a greater distance between the nucleus and the outermost orbital. This results in a larger atomic radius.
Why does atomic size generally increase as you move down a group of the periodic table and decrease as you move from left to right across a period?
Moving Across the Periodic Table. an increase in atomic size
because of additional repulsions between electrons
, a decrease in size because of the additional protons in the nucleus, no effect at all as the two opposing tendencies of electron repulsion and nuclear attraction balance each other out.
Why does atomic size increase as you go down a group quizlet?
Why does atomic radii increase as you move down a group?
The number of energy levels increases
as you move down a group as the number of electrons increases. Each subsequent energy level is farther from the nucleus than the previous one. Therefore, the atomic radius increases as the group and energy levels increase.
Why does atomic size decrease as you go from left to right across a period?
Atomic size gradually decreases from left to right across a period of elements. … This means that the
nucleus attracts the electrons more strongly
, pulling the atom’s shell closer to the nucleus. The valence electrons are held closer towards the nucleus of the atom. As a result, the atomic radius decreases.
Why do atoms get smaller as you move left to right in a period quizlet?
Why do atoms get smaller as you move left to right in a period?
The # of protons increase, so electrons are more attracted to the nucleus, so the atomic radius is smaller
.
Why do both atomic size and ionic size increase as you move down a group?
Basically, as we move down the periodic table,
the size of the nucleus increases
, and concomitantly more electrons are present to “shield” the valence electrons from the charge. … If there are many electrons, its harder to rope them up via electron charge than when there are less.
Does Zeff increase down a group?
Going down a group, distance and shielding increase. Effective Nuclear Charge (Zeff) remains constant. … Ionization energy
decreases going down a group
. Going down a group, distance and shielding increase.
Which element is most essential for life?
Oxygen
.
Oxygen
is the most abundant element contained within living organisms, composing about 65% of the human body. Oxygen is also the most abundant element in the Earth’s crust, and in the air that is essential for most life on Earth.
What is the trend for atom size from top to bottom down a group?
The atomic radius of atoms generally
increases
from top to bottom within a group. As the atomic number increases down a group, there is again an increase in the positive nuclear charge. However, there is also an increase in the number of occupied principle energy levels.
Which group has high atomic size?
Answer: The atomic radius increases from top to bottom in a group, and decreases from left to right across a period. Thus, helium is the smallest element, and
francium
is the largest.
Does atomic size increase or decrease from top to bottom down a group?
The atomic radius of atoms generally
increases from top to bottom
within a group. As the atomic number increases down a group, there is again an increase in the positive nuclear charge.
What is the trend in EA across a period?
Electron affinity generally
increases across
a period in the periodic table and sometimes decreases down a group. These trends are not necessarily universal. The chemical rationale for changes in electron affinity across the periodic table is the increased effective nuclear charge across a period and up a group.
What is the trend in atomic radii as you move from left to right across a period quizlet?
Across a period from left to right,
the covalent radius decreases
. As you move from left to right across the periodic table, atoms have more electrons in their outer energy level and more protons in their nucleus. … As you move down a group in the periodic table, the covalent radius increases.
Why are helium and hydrogen exceptions to the octet rule?
The main exception to the rule is hydrogen, which is at its lowest energy when it has two electrons in its valence shell.
Helium (He) is similar in that it
, too, only has room for two electrons in its only valence shell. … Therefore, these elements are most stable when they have two electrons.
What increases as you move across a period from left to right?
Moving Across a Period
Moving from left to right across a period, the atomic radius decreases. The nucleus of the atom gains
protons
moving from left to right, increasing the positive charge of the nucleus and increasing the attractive force of the nucleus upon the electrons.
What is an atom called when it loses or gains electrons?
When an atom gains/loses an electron, the atom becomes charged, and is called
an ion
. Gaining an electron results in a negative charge, so the atom is an anion. Losing an electron results in a positive charge, so atom ion is a cation.
