Periodic Table & Periodicity of Properties Flashcards
who discovered atomic number?
Moseley
what are the horizontal rows called in the periodic table?
periods
what are the vertical columns called in the periodic table?
group or family
what are the first three periods called?
short periods
what are group A elements called?
Representative elements
what are group B elements called?
Transition elements
periodic table is arranged according to ___________?
increasing atomic no.
number of protons
why He is not placed after H?
He has different chemical properties & has to be grouped accordingly
if group of elements have same chemical properties then what is similar?
they have same valence electrons which = same chemical properties & that’s why are grouped in a group/family
majority of element in the periodic table are _______?
metals
minority of element in the periodic table are _______?
non-metals
is H metal or non-metal
non-metal
Group IA elements are called?
alkali metals
what group of elements is called halogens?
7th group
group VIIA elements are called?
halogen
group VIIIA elements are called?
noble gases
elements that have similar chemical properties lie in the same ______ in the periodic table.
column/group
how many periods are there in the periodic table?
7
how many groups are there in the periodic table?
18
8
what does the period tell us?
no. of shells
what does the group tells us?
no. of valence electrons in an element
group IA and group IIA elements are called?
s-block elements
group IIIA to group VIIIA elements are called?
p-block elements
(except He)
what is a metalloid?
Metalloids, also known as semimetals, are a group of elements that exhibit properties that are intermediate between metals and nonmetals. They are located along the diagonal “staircase” region on the periodic table, separating the metals on the left from the nonmetals on the right.
name metalloids?
8
Boron (B)
Silicon (Si)
Germanium (Ge)
Arsenic (As)
Antimony (Sb)
Tellurium (Te)
Polonium (Po) (optional)
Astatine (At)
what is shielding effect
reduction in the attractive force between the +vely charged nucleus of an atom and its valence e- by the e- present in the inner shells.
The shielding effect is the __________ in the attractive force between the nucleus and the outer electrons due to the presence of inner electrons.
reduction
The shielding effect results in a __________ effective nuclear charge experienced by the outermost electrons compared to the actual charge of the nucleus.
reduced
The shielding effect causes larger atomic sizes because the outermost electrons are held __________ tightly by the nucleus.
less
Moving down a group in the periodic table, the shielding effect __________
increases
The shielding effect primarily affects which atomic property?
Atomic size
what is the size of an atom?
average distance between the nucleus and the valence shell.