Writing and balancing chemical equations Flashcards
(20 cards)
How do you find the charge of elements in an ionic compound?
Most ionic compounds contain a metal and non-metal. Metals lose outer shell electron and become positively charged. Non-metals gains electrons and become negatively charged. E.g Li has 1 outer electron so loses it and become positively charged by one. Nitrogen has 5 outer electrons so gains 3 and becomes negatively charged by 3.
How do you write the formula of an ionic compound?
Use the cross method. If the compound is aluminium oxide, the charge is Al3+ and the charge of oxide is O2- so cross the numbers and the formula becomes Al2O3.
What are the properties of the alkali metals?
- They are soft and can be cut by a knife
- They have a low density, lithium, sodium and potassium float on water
- They have lower melting and boiling points than other metals, which decrease going down the ground, as the atoms become larger, attraction to the nucleus becomes weaker and reactivity increases
- They all have 1 outer electron
What are the alkali metals?
Lithium - Li Sodium - Na Potassium - K Rubidium - Rb Caesium - Cs Francium - Fr
How do alkali metals react with oxygen?
All alkali metals react with oxygen in the air to form metal oxides.
The speed with which alkali metals react with oxygen increase going own the group.
How are alkali metals stored?
In oil to prevent them from reacting with oxygen and tarnishing.
Why are they called alkali metals?
Alkali metals react with water to produce heat, hydrogen gas, and the corresponding metal hydroxide. The heat produced by this reaction may ignite the hydrogen or the metal itself, resulting in a fire or an explosion.
What is an isotope?
Atoms with different numbers of neutrons are called isotopes.
What are the properties of isotopes?
Isotopes mainly have similar or the same chemical properties as chemical properties are based on electrons but mass will be different and may or may not be radioactive.
What are the properties of the Halogens?
- They have low melting points and boiling points. Their melting points and boiling points increase going down the group
- They are poor conductors of heat and electricity
What are the Halogens?
Fluorine - F Chlorine - Cl Bromine - Br Iodine - I Astatine - At
In Group 7 (the Halogens) what is the unique trend going down the group?
The reactivity decreases going down.
What do the halogens form in their ionic compounds with metals?
They all form ions with a single negative charge.
What do the halogens form with other non-metals?
They form covalent compounds by sharing electrons with other non-metals.
What happens in a reaction with a more reactive and less reactive halogen in a solution of one of its salts?
The more reactive halogen DISPLACES the less reactive halogen.
What is electrostatic force?
Electrostatic attraction is what you get between oppositely charged ions in a giant ionic lattice, e.g. NaCl, where the Na+ and Cl- ions are attracted to one another. Electrostatic attraction is not an intermolecular force, as it is not between molecules.
What is intermolecular force?
Intermolecular forces occur between simple covalent molecules, e.g. H2O, and CH4. Intermolecular forces are very weak in comparison to a covalent / ionic bond, and therefore can be broken easily. That is why the melting / boiling temperatures of simple covalent molecules is low.
Why do the halogens decrease in reactivity going down the group?
Non-metal atoms gain electrons when they react with metals. … The electrons in the outer shell move further away from the nucleus as we go down the group and the attraction force between the electrons and the nucleus become weaker and weaker.
What are the properties of the transition metals?
- They are good conductors of electricity and thermal energy
- They are hard and strong
- They have high densities
- They have high melting points (except mercury, liquid at room temp
- They are harder, stronger and denser than the alkali metals but less reactive
What do transition metals form in compounds that are often coloured?
A transition element can form ions with different charges e.g iron can be Fe2+ or Fe3+
