This is a hard question because BEING BOLD cant be light ya know... but the light bulb.. thomas edison and joseph swan
Explanation:
The periodic table is a table that arranges elements based on their atomic numbers into groups and periods.
The groups are the vertical arrangement of elements. All elements in a group share similar chemical properties because they have the same number of elements in their valence shell. The periodic table groups are:
Group Other names
1A or 1 Alkali metals
IIA or 2 Alkaline earth metals
IIIA or 3 Boron family
VIA or 6 Chalcogens
VIIA or 17 Halogens
O-18 Inert elements
IIIB-IIB Transition elements
There are 18 vertical columns divided into 8 tall groups or main groups which are 1A to O. The short groups or subgroups are from numerals 1B to VIII.
The periodic table can be divided into four blocks based on the type of sublevels their valence electrons occupy.
- Group IA and IIA constitute the s-block
- Group IIIA to O constitute the p-block
- The transition elements makes up the d-block
- The lanthanides and actinides makes up the f-block
Learn more:
Periodic table brainly.com/question/2014634
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Given mass of Scandium = 50.0 g
Increase in temperature of the metal when heated = 
Heat absorbed by Scandium = 
The equation showing the relationship between heat, mass, specific heat and temperature change:

Where Q is heat = 
m is mass = 50.0 g
ΔT = 
On plugging in the values and solving for C(specific heat) we get,
=50.0g(C)(
)
C = 0.491
Specific heat of the metal = 0.491
<u>Halogens are reactive because:</u>
They have high electronegativity and also high nuclear charge. So, they are reactive and also gain an electron when they react with other elements.
Since they are very reactive, halogens are very harmful to living organisms. Some of the halogens are fluorine, chlorine, bromine, iodine, astatine. These are mostly non metals. Fluorine is one of the most reactive gas and also very toxic gas. When Fluorine reacts with glass along with small amounts of water, it forms silicon tetra fluoride (SiF4). Hence fluorine should be handled with substances like the inert organofluorine compound Teflon.