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.
In an ionic bond, when the metal atom has a single electron in its outer shell and the non-metal needs an electron to complete its outer shell, the metal atom gives its electron to the non-metal. Similarly, in the covalent bond, they share the electron equally. Ionic Bond. Covalent Bond. Definition. A chemical bond between two dissimilar atoms in which atom gives up an electron to another. A covalent bond is a chemical bond that involves the sharing of electrons between two similar atoms.