Equations, Group Trends in Periodic Table

Seite 1

Reactant + Reactant --> Product

Word equation doesn't tell you anything about the proportions in which they react

St

State symbols

solid (s)

liquid (l)

gas (g)

Substance is dissolved in water - aqueous (aq)

Symbol equation tells us:

- which substances are the reactants

- which substances are the products

- the formula of all the substances involved in the reaction

- numbers of moles of all the substances involved

- states of all the substances

Rules:

1. Write the word equation

2. Convert the words into the correct chemical formulae (gaseous elements except for noble gases are diatomic)

3. Fill in the state symbols

4. Balance the equation

- same number of atoms before and after reaction

- do not change chemical formulae to balance the equation

- only placing whole numbers in front of the formulae can change the proportions of the reactants and products

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- When an ionic compound OR strong acid dissolves in water it DISSOCIATES into IONS and becomes a conductor of electricity

- When these solutions react, the molecular equation can be simplified by writing an ionic equation

HCl (aq) + NaOH (aq) --> NaCl (aq) + H2O (l)

atoms/molecules that didn't change state didn't react = spectator ions

Spectator Ions: Cl + Na

Net Ionic Equation doesn't include spectator ions

= H (aq) + OH (aq) --> H2O (l)

Elements are ordered by atomic number (represents the number of protons)

Groups: vertical columns where elements have the same number of valence electrons

- have similar chemical and physical properties

Periods: horizontal rows where electrons are filling the same energy level/shell

Metals on the left = metals

metals on the right = non-metals

Metalloid = chemical elements that aren't classified

pH of period 3 oxides

- going across the groups the pH decreases

- metals are basic

- non-metals are acidic or neutral

- acidic = sulphur dioxide (dissolves in water to form acid rain)

- neutral = hydrogen oxide (water) and carbon monoxide

All oxides of metals can act as bases, but some can act as acidic oxides as well = amphoteric oxides

3

4 types of oxides:

- basic:

-- lithium oxide

-- sodium oxide

- acidic

-- sulphur oxide

-- chlorine oxide

- neutral

-- carbon monoxide

-- hydrogen oxide (water)

- amphoteric

-- aluminum oxide

-- zinc oxide

Noble Gases

- unreactive gases (full electron shell)

- 1% of the earth's atmosphere

- non-metals

- colorless gases

Oxides are used to determine whether an element is a metal or a non-metal.

Most non-metals are classed as acidic oxides. While most metals are classed as basicoxides.

Acidic Oxides

Reacts with water to form acids

Neutralises alkaline solution to form salt + water

Basic Oxides

Neutralises acidic solutions to form salt + water

Amphoeteric Oxides

These are non-metals which display both acidic and basic properties

Alkaline Oxides

Reacts with water to form alkaline solutions

Neutral Oxides

Do not display either of the acidic or the basic oxides’ properties.

Lithium:

Bubbles seen

H2 released

Disappears

Sodium:

Melts and forms a ball as the reaction is exothermic. The heat causes the sodium to melt.

Same as Lithium

Potassium:

Lilac flame seen as the hydrogen burns.

Same as sodium

Reacting with water (Mr Rowcliffe ran)

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stor

- stored in oil so that they don't react with oxygen

- rusted quickly once exposed to air

- hydrogen is produced when they react with water

- hydroxides are formed (OH)

Potassium > Sodium > Lithium

Reactivity of group 1 metals increase going down the group

all metals rect with water to form strong alkaline solutions

melting point and hardness decreases as you go down the group

Equations

Net Ionic Equations

Periodic Table

More on Oxides

Group 1