Chemistry Flashcards
1
Q
What are atoms?
A
The smallest particle of a chemical element.
2
Q
What is the periodic table?
A
The arrangement of all known elements in order of atomic number.
3
Q
What are groups in the periodic table?
A
- Groups refer to the vertical columns in the periodic table.
- Group number = the number of valence electrons.
- elements in the same group share similar properties.
4
Q
What are periods in the periodic table.
A
- Periods refer to the horizontal rows in the periodic table.
- Period number = the number of electron shells.
5
Q
Describe metals, non-metals, and metalloids.
A
- Metals are elements that tend to lose electrons (found on left side of the periodic table).
- Non-metals are elements that tend to gain electrons (found on right side of the periodic table.
- Metalloids are elements with properties of both metals and non-metals.
6
Q
Describe electronegativity.
A
- An atoms ability to gain electrons.
- higher electronegativity = more likely to gain electrons.
- increases across a period.
- decreases down a group.
7
Q
Describe electron shells.
A
- Different energy levels within the atom that hold electrons
- closer to the nucleus = lower energy
- further from the nucleus = higher energy.
8
Q
Describe ionic bonding.
A
- Ionic compounds formed from the transfer of electrons between a metal and a non-metal
- Ions are charged atoms that have lost or gained electrons
- Ionic bond is an electrostatic connection between a positive and negative ion.
- Cations - positively charged (lost electrons)
- Anions - negatively charged (gained electrons)
- High electronegativity (non-metals) will gain electrons
- Low electronegativity (metals) will lose electrons
- Swap and drop
9
Q
Describe covalent bonding.
A
- Molecules formed between a non-metal and a non-metal as a result of sharing electrons.
- shared electrons are attracted to the positive nuclei.
- not as strong as ionic bonds.
- Single bond - each atom shares one electron (2)
- Double - each atom shares two electrons (4)
10
Q
Describe the characteristics of an electron dot diagram and structural diagram.
A
- Used to illustrate covalent bonds
- Electron dot diagram includes all valence electrons.
- Structural diagrams only show covalent bonds.
11
Q
Describe chemical reaction.
A
- Atoms are rearranged, substances break bonds to form new bonds, producing a new substance.
- Indicators:
- colour change
- gas production
- form precipitate (solid)
- energy is produced or absorbed (heat/sound/light)
12
Q
Word equations.
A
- Describe chemical reactions by writing full name of reactants and products.
- E.g. Hydrochloric acid + sodium hydroxide –> sodium chloride + water.
13
Q
Law of conservation of mass.
A
- Matter cannot be created or destroyed, only changed in form.
- Number/type of atoms must be balanced for reactants and products.
13
Q
Chemical equations.
A
- Use formula to show how atoms in reactants rearrange to form products.
- E.g. HCl(aq) + NaOH(aq) –> NaCl(aq) + H20(l)
14
Q
Exothermic and Endothermic reactions.
A
- Exothermic reactions:
- Release energy into surroundings
- Release heat/light/sound
- less energy in products than reactants.
- Endothermic reactions:
- Absorb energy from the surroundings
- Cold surroundings / cold test tube
- More energy in products than reactants.
15
Q
Decomposition reaction.
A
- a single compound breaks down into two or more elements.
- AB –> A + B
- CuCO3(s) –> CO2(g) + CuO(s)
16
Q
Synthesis reaction.
A
- two or more reactants combine to form one product.
- A + B –> AB
- 2H2(g) + O2(g) –> 2H20(l)
17
Q
Single displacement reaction.
A
- an element reacts with a compound, replacing one element within that compound.
- A + BC –> AC + B
- Fe(s) + CuSO4(aq) –> Cu(s) FeSO4(aq)
18
Q
Double displacement reaction.
A
- two compounds react, the positive cations and negative anions in the two reactants switch places, forming two new substances.
- AC + BD –> AD + BC
- CuSO4(aq) + 2NaOH(aq) –> Cu(OH)2(s) + Na2SO4(aq)
19
Q
Precipitation reaction.
A
- a type of double displacement reaction
- soluble aqueas solutions react to form an insoluble solid.
- 2KI(aq) + Pb(NO3)2(aq) –> PbI2(s) + 2KNO3(aq)
20
Q
Combustion reaction.
A
- Hydrocarbon reacts in the presence of oxygen to produce carbon dioxide and water vapour (and heat)
- Hydrocarbon + Oxygen –> Carbon dioxide + Water
- CH4(g) + 202(g) –> CO2(g) +2H20(g)
21
Q
Neutralisation reaction.
A
- An acid and a base react to produce water and a salt
- Acid + Base –> Water + Salt
- H2SO4(aq) –> 2NaOH(aq) –> 2H2O(l) + Na2SO4(aq)
22
Q
Collision theory.
A
- For a chemical reaction to occur:
- particles must collide
- with proper orientation
- colliding with enough energy to meet minimum activation energy.
23
Q
Activation energy.
A
The minimum amount of energy required at which a collision will turn reactants into products.
24
Rate of reaction.
- Chemical reactions occur at different rates.
- Rate of reaction refers to the speed at which a chemical reaction proceeds.
25
Describe how agitation affects rate of reaction.
- As a chemical reaction progresses the reactant particles are used up.
- The fewer reactant particles = the fewer collisions occur causing the reaction rate to slow.
- Agitation increases particle moment, causing collisions to occur more frequently, increasing the rate of reaction.
26
Describe how surface area affects rate of reaction.
- In solid reactants only particles exposed at the surface can react.
- Smaller particles have a larger surface area than larger particles, exposing more of the substance to reactants.
- Increasing surface area increases frequency of collisions, increasing rate of reaction.
27
Describe how temperature affects rate of reaction.
- Increasing temperature increases kinetic energy of particles causing particles to move faster.
- The faster particles move, the more frequently collisions will occur, increasing the rate of reaction.
28
Describe how concentration affects rate of reaction.
- Concentration refers to the number of particles present in a particular volume.
- Increasing the concentration of reactant particles increases the frequency of collisions, resulting in an increased rate of reaction.
29
Describe how catalysts affects rate of reaction.
- A catalyst is a chemical that speeds up a chemical reaction without being consumed.
- Catalysts increase the rate of reaction by temporarily binding to reactants, providing proper orientation for a successful collision to occur.
- or provide an alternative reaction pathway with lower activation energy, increasing the number of successful collisions.
- Increasing the number of successful collisions increases the rate of reaction.
