Properties of Water TSW describe the properties of water that make it essential to life on Earth

What is water? H2O…which means? 1 molecule of water has 2 atoms of Hydrogen & 1 atom of Oxygen Water covers up to 75% of the Earth’s surface & makes up 70-95% of all living cells!

Atomic Structure 2H + O → H2O Each Hydrogen atom is held onto the Oxygen atom by a polar covalent bond

Let’s take it a step further… Hydrogen Protons: 1 Neutrons: 0 Electrons: 1 Oxygen Protons: 8 Neutrons: 8 Electrons: 8

Types of Bonding Ionic Covalent Polar Covalent Hydrogen

Ionic Bonding Forms when 1 or more electrons are transferred from one atom to another If P > E → (+) charge If P < E → (-) charge Example: NaCl

Covalent Bonding Forms when electrons are shared between atoms NOT transferred, the resulting structure is called a molecule Example: HCl or H2

Polar Covalent Bonding Forms when sharing occurs in an unequal manner (the molecule formed has no net charge) Opposite ends of the molecule are partially (-) & partially (+) depending on the distribution of electrons Example: H2O

Good to know… Covalent bonds are stronger than ionic bonds Covalent bonds do not dissociate in water

Hydrogen Bonding Forms between water molecules H+ bonds to O- Easy to break Key Point: The numerous special qualities of water are made possible by its ability to form multiple H bonds