Valence electrons. 1  The highest principal shell of an atom, in which there is at least one electron, is called the valence shell. 2  The electrons on the valence shell are called valence electrons. 3  Main group elements can hold a maximum of eight electrons in their valence shell. A full valence shell is known as an octet.
Novella. A novella is a written, fictional, prose narrative normally longer than a short story but shorter than a novel. The English word novella derives from the Italian word novella, feminine of novello, which means new. The novella is a common literary genre in several European languages.
A novel means a book-length story. In between is the novella: you might fit 3 or 4 novellas into a reasonable-length book. If a story takes more than one book, it becomes a series. If there are exactly three books in the series, it's called a trilogy.