A zygote is the initial cell formed after a sperm and egg have joined. A blastocyst begins at day 5 in mammals after fertilization. This all occurs during the first week of being conceived. After the first week, the developing life form becomes an embryo, and the embryo is the stage where DNA is built..After week 9 in a human lifeform, it is considered a fetus. zygote is the initial cell formed after a sperm and egg have joined. A blastocyst begins at day 5 in mammals after fertilization. This all occurs during the first week of being conceived. After the first week, the developing life form becomes an embryo, and the embryo is the stage where DNA is built..
A covalent chemical bond results from the sharing of electrons between two atoms with similar electronegativities A single covalent bond represent the sharing of two valence electrons (usually from two different atoms). The Lewis structure below represents the covalent bond between two hydrogen atoms in a H2 molecule.
2Covalent bond. The most common bond in organic molecules, a covalent bond involves the sharing of electrons between two atoms. The pair of shared electrons forms a new orbit that extends around the nuclei of both atoms, producing a molecule.