Ionic bonds: when atoms give and take electrons

0:00Sodium and chlorine make sodium chloride, or table salt. What holds it together?

0:07A Bohr diagram shows the electrons in shells around the nucleus.

0:12Sodium has eleven electrons: two, then eight, then one in the outer shell.

0:19Chlorine has seventeen electrons: two, eight and seven.

0:24Atoms are more stable with a full outer shell: eight electrons for these atoms.

0:30Sodium has one electron to lose, and chlorine needs one more.

0:35So sodium gives its outer electron to chlorine.

0:39Sodium now has eleven protons but only ten electrons: a charge of plus one.

0:46Chlorine now has seventeen protons and eighteen electrons: a charge of minus one.

0:53Charged atoms are called ions: a sodium ion and a chloride ion, both with a full outer shell.

1:01Opposite charges attract. This pull between the ions is called an ionic bond.

1:08The electron is not shared. It moves from sodium to chlorine.

1:13In ionic bonds, metals lose electrons and non-metals gain them.

1:19In salt, many ions pack into a repeating pattern called a lattice, not molecules.

1:26These strong attractions give ionic compounds high melting points. Table salt melts at 801 degrees Celsius.

1:34Melted or dissolved in water, the ions can move, so ionic compounds conduct electricity.

1:42So in an ionic bond, metals give electrons, non-metals take them, and the opposite ions attract.