Chapter 3 Flashcards
How many types of bonding are there?
3 - metallic, covalent and ionic
How are ionic bonds formed?
Strong electrostatic attraction between positive and negative ions
How are metallic bonds formed?
Strong electrostatic attraction between the -ve electrons in the ‘sea of electrons’ and the +ve metal ions
How are covalent bonds formed?
Strong electrostatic attraction between the shared - ve electrons and the +ve protons in the nucleus
What do ionic compounds form?
Giant lattice structures
What are macromolecules?
Giant colvalent structures such as diamond, graphite, graphene and silicon dioxide
What are simple covalent molecules?
Small molecules formed from two or more non-metals bonded together e.g. H2, CO2, H2O
How do negative ions form?
Non-metals gain electrons
How do positive ions form?
Metals lose electrons
How do you work out the charge on a -ve ion?
8 - the group number
How do you work out the charge on a +ve ion?
The group number
What are dot and cross diagrams?
Diagrams to show the movement of electrons between atoms
Name some properties of small covalent molecules?
Small molecules are usually gases or liquids that have relatively low melting points and boiling points. These substances have only weak forces between the molecules (intermolecular forces)
Name some properties of macromolecules?
Substances that consist of giant covalent structures are solids with very high melting points. All of the atoms in these structures are linked to other atoms by strong covalent bonds
Why do covalent molecules not conduct electricity?
Because they do not have charged particles that are free to move (exception is graphite)
What is an alloy?
When a metal is mixed with another metal or non-metals such as carbon to alter its properties
Why can graphite conduct electricity?
Because it has delocalised electrons sitting between the carbon layers. These -ve charged electrons are free to move
How can we find the ionic formula of a compound?
Use the crossover rule
What is a fullerene?
The fullerenes are a large class of allotropes of carbon and are made of balls, ‘cages’ or tubes of carbon atoms
What is an allotrope?
Different structural forms of carbon e.g. graphite, diamond, fullerenes
What is the abbreviation for an aqueous Solution?
aq
What is the state symbol for a gas?
g
What is the state symbol for a solid?
s
Covalent bonding is the ……..
The attraction between two atoms that share one or more pairs of electrons
Ionic bonding is……………………………
The electrostatic force of attraction between positively and negatively charged ions
What are intermolecular force?
The attraction between one MOLECULE and a neighbouring MOLECULE
What is the empirical formula?
The simplest ratio of elements in a compound
What is a mixture?
When some elements or compounds are mixed together and intermingle but do not react together (i.e. no new substance is made). A mixture is not a pure substance.
Metals conduct electricity because…..
They have free electrons that can move.
Metals are strong because….
They have strong metallic bonds.
Metals are malleable and ductile because…..
They have layers of atoms that can slide over each other.
In covalent molecules, a pair of shared electrons form a ….. bond
Single bond
In covalent molecules, two pairs of shared electrons form a ….. bond
Double bond
In covalent molecules, three pairs of shared electrons form a ….. bond
Triple bond
What are intramolecular forces?
Forces between ATOMS in a compound
What are the states of matter?
Solids, liquids and gases
Why are alloys often stronger?
Because the layered structure is disrupted and layers can no longer slide over each other
A heating curve is a line graph showing the temperature of a substance plotted against the amount of energy it has absorbed. It represents the change of state of matter, typically from a solid to a liquid to a gas.
In a heating curve, what do the flat areas (plateaus) on the graph represent?
The flat areas represent a change in state - energy is being used to change state so you see no increase in temperature
Is this a graph of a cooling or heating curve?
Cooling
