Identify the group or period number described by each of the...

Identify the group or period number described by each of the following:
a. contains the elements $\mathrm{C}, \mathrm{N}$, and $\mathrm{O}$
b. begins with helium
c. contains the alkali metals
d. ends with neon

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Key Concepts

Noble Gases

Noble gases occupy Group 18 of the periodic table and are noted for their full valence electron shells, which make them particularly stable and chemically inert. Their placement in this group explains why elements like helium and neon have minimal tendency to engage in chemical reactions.

Alkali Metals

Alkali metals, which are found in Group 1 of the periodic table, are characterized by having a single electron in their outermost electron shell. This gives them high reactivity, as they readily lose that electron to form positive ions.

Periods

Periods are the horizontal rows in the periodic table. Each period corresponds to the number of electron shells an element’s atoms possess, and elements within a period typically show a progression in properties, such as atomic size and ionization energy.

Periodic Table Organization

The periodic table is arranged into periods (horizontal rows) and groups (vertical columns), and this organization reflects periodic trends in electron configurations and chemical properties across the elements.

Groups

Groups are the vertical columns in the periodic table where elements share similar chemical properties due to having analogous valence electron configurations. Group numbers provide insights into reactivity, bonding behavior, and other chemical characteristics.

Transcript

00:01 So first of all we have given elements c and o.

00:06 So carbon has atomic number 6, nitrogen has 7 and oxygen has 8.

00:11 So the electronic configuration will be 1s2 2s2 2p2 and for this we will have 1s2 2s2 2p3 then for oxygen we have 1s2 2s2 2p4.

00:36 I hope you noticed something that is the last electron enters in second shell.

00:43 So that's why we have here therefore since the last electron enters in second shell hence all are from second period okay that is period 2 okay.

01:55 So see what we have given here in these parts we have to find the common thing in all of them okay.

02:03 So the common thing between all these atom that is period.

02:06 So we have to identify here for period okay.

02:09 So period is second.

02:10 Now we have given begins with helium.

02:15 So that is group 18 that is the group of noble gases which begins from helium.

02:23 Helium is itself a noble gas.

02:26 So in this case group 18 begins with helium okay and is group of noble gases okay.

03:07 Moving on to c part contain the alkali metals.

03:13 Now as i told you before that we have to find the common thing right.

03:17 So contains the alkali metal.

03:20 So alkali metal have a separate group and that group is group 1st...