Checkup on Chapter 4 Flashcards
Explain the difference between an element and a compound.
Elements are composed of only one type of atom wheras compounds are made up of two or more different types of elements.
What are the signs of a chemical change?
1 One or more new chemical substances are formed.
2 Energy is taken in or given out during the reaction.
3 The change is usually difficult to reverse.
Explain why atoms of Group VIII elements do not form bonds.
The atoms of Group VIII elements do not form bonds because they already have the desired 2 or 8 valence electrons which makes them unreactive and stable.
Explain why atoms of other elements do form bonds.
Atoms of other elements bond with each other on order to gain a stable arrangement of outer shell electrons, like the atoms of Group VIII.
Explain the difference between an ionic bond and a covalent bond.
Ionic bonds form when two or more ions come together and are held together by charge difference.
Covalent bonds form by the sharing of electrons between two or more atoms.
The particles in ionic bonding are ions.
The particles in covalent bonding are molecules.
What is a molecule?
A molecule is a structure made up of two or more atoms covalently bonded together.
Who do the non-metal atoms form covalent bonds with?
Non- metal atoms form covalent bonds with each other
Describe how this property differs for ionic and molecular compounds: melting and boiling points.
Ionic compounds have high melting and boiling points whereas molecular compounds have low melting and boiling points.
Describe how this property differs for ionic and molecular compounds: solubility.
Ionic compounds are usually soluble in water whereas covalent compounds tend to be insoluble in water. They are soluble in some solvents.
Describe how this property differs for ionic and molecular compounds: ability to conduct electricity.
Ionic compounds conduct electricity, when melted or dissolved in water whereas Covalent compounds do not conduct electricity.
