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.
Unlike ionic bonding, covalent bonding may have single, double bonds or triple bonds between two atoms. These bonds are formed in such a way that the two atoms obey the octet rule. The bond occurs via the overlapping of atomic orbitals. A single bond is formed when two electrons are shared. A double bond is formed when four electrons are shared. Sharing of six electrons may result in a triple bond. The characteristics of compounds with covalent bonds include strong bonding between two atoms due to similar electronegativity values.