chemistry chapter 4 bonding Flashcards
what is ionic bonding
a strong electrostatic attraction between oppositely charged ions
how are ions formed
an atom becomes an ion when it gains or loses electrons
how are positive ions formed
when an atom loses electrons, it has less electrons than protons forming a positive ion, also known as cation. Therefore, positive ions or cations are formed when an atom loses electrons
how are negative ions formed
when an atom gains electrons, it has more electrons than protons forming a negative ion also known as anions. Therefore negative ions or anions are formed when they gain electrons.
how are ionic compounds formed
when a metal reacts with a non metal, the metal atoms transfer their outer electrons to the non metal atoms forming cations and anions
what are the physical properties of ionic compounds
- are crystalline solids
- have high melting and boiling points
- have a good electrical conductivity when molten or in aqueous solution
what is a giant lattice structure
a three dimensional network of ions. the ions are held in place by ionic bonds and are packed in a regular and a repeating pattern. The giant lattice structure is held tightly because oppositely charged ions attract one another strongly
what is a covalent bond
when non metallic elements react with one another, they share electrons in order to achieve the noble gas electronic configuration
covalent bonds can be formed between
atoms of the same element and different elements
what are the physical properties of simple molecules
- have low melting and boiling points
- are poor electrical conductors
what are the physical properties of giant covalent substances
- high melting and boiling points
- do not conduct electricity except graphite
what is a giant covalent structure
a three dimensional regular arrangement of atoms or molecules joined by strong covalent bonds
give an example of a giant covalent structure
diamonds and graphite
why do giant covalent substances have high melting and boiling points
a giant covalent structure consists of a large number of atoms that are held together by strong covalent bonds. To melt or boil these substances, the strong bonds must be broken. This requires a lot of energy meaning that these substances will have high melting and boiling points making them solids at room temperature
why do giant covalent substances not conduct electricity
in giant covalent substances, all the outer electrons of atoms are used to form covalent bonds, Thus, there are no delocalised electrons that move through the structure to conduct electricity
