I'm guessing that you're talking about Hydrogen, Oxygen, Bromine, Flourine, Iodine, Nitrogen, and Clorine. They are all diatomic molecules. When found in their pure states, the consist of two atoms bonded together. This is why oxygen is O2, Hydrogen is H2, and so on.
A common mnemonic for remembering them is that you make a "7" on the Periodic Table, starting with the 7th element, nitrogen. Then you just have to remember Hydrogen.
I remember HOBrFINCl, which is pronounced "Hoberfinkle". I think it's easier, and it doesn't require a periodic table.
periodsThere are seven periods, or rows, on the periodic table.
The seven horizontal rows of the table are called periods. Elements in the same row have the same number of electron shells, which determines their chemical properties.
The horizontal rows are called periods, there are 7. The vertical rows are groups and there are 18.
It is The Periodic Table of Elements
halogens (group 17 elements)
There are more than 3 elements in group seven, and they are called halogens.
periodsThere are seven periods, or rows, on the periodic table.
The seven horizontal rows of the table are called periods. Elements in the same row have the same number of electron shells, which determines their chemical properties.
Group 7 elements are examples of transition metals (or d-block elements)
periodsThere are seven periods, or rows, on the Periodic Table.
Strive to uphold
Super Seven Calling Cairo was created in 1965.
The duration of Super Seven Calling Cairo is 1.58 hours.
Not to be confused with Super Mario RPG: Legend of the Seven Stars on the Super Nintendo Entertainment System, also known as Super NES and SNES, Super Mario RPG The Seven Sages is downloadable on the PC for free.
Los Super Seven - album - was created on 1998-09-15.
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"Super Mario RPG: Legend of the Seven Stars" features the Seven Sages. This classic role-playing game was originally released for the Super Nintendo Entertainment System (SNES) in 1996. It combines traditional RPG elements with the beloved Mario universe, allowing players to experience a unique storyline and turn-based combat.