Research suggests that crochet probably developed most directly from Chinese needlework, a very ancient form of embroidery known in Turkey, India, Persia and North Africa, which reached Europe in the 1700s and was referred to as tambouring, from the French tambour or drum.
POLAR BONDS. 1) Covalent bond between two atoms with unequal electronegativities results in unequal sharing of electrons. 2) Unequal electron sharing leads to partially positive and partially negative charges on opposite ends of the bond.When the two atoms involved in a covalent bond both have equal affinity for electrons, the electrons in the bond are evenly shared between them.hese types of covalent bonds are called polar bonds because the electron distribution or charge is unevenly distributed or polarized. Partial charges are represented by lower case delta (+) Î´+ or lower case delta (-) Î´-. A separation of partial charges within a polar covalent bond is referred to as a dipole.
When the electronegativities are not equal, electrons are not shared equally and partial ionic charges develop. Nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.The greater the electronegativity difference, the more ionic the bond is. Bonds that are partly ionic are called polar covalent bonds.Nonpolar covalent bonds.onpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.