Chemistry new flashcards

What is an anion?

A negatively charged ion formed when an atom gains electrons.

What is a cation?

A positively charged ion formed when an atom loses electrons.

How do you tell if a particle is an anion or cation?

If it has more electrons than protons it is an anion; if it has fewer electrons than protons it is a cation.

What is empirical formula?

The simplest whole-number ratio of atoms in a compound.

How do you find empirical formula?

Convert each element to moles, then divide by the smallest value to get the simplest ratio.

What is the reactivity series?

A list of metals arranged from most reactive to least reactive.

What is the reactivity series in order?

Potassium, sodium, calcium, magnesium, aluminium, carbon, zinc, iron, hydrogen, copper, silver, gold.

Why is the reactivity series useful?

It helps predict reactions with water, acids, and metal salt solutions.

What is ionic bonding?

The electrostatic attraction between oppositely charged ions.

How is ionic bonding formed?

By transfer of electrons from a metal to a non-metal.

What is covalent bonding?

The attraction between atoms when they share pairs of electrons.

How is covalent bonding formed?

By sharing electrons between non-metal atoms.

How do you identify whether bonding is ionic or covalent?

Metal + non-metal usually forms ionic bonding; non-metal + non-metal usually forms covalent bonding.

Why do ionic compounds have high melting points?

Strong electrostatic forces between ions need a lot of energy to overcome.

Why do ionic compounds conduct electricity when molten but not when solid?

When molten the ions are free to move, but in the solid they are fixed in place.

What is oxidation?

Loss of electrons.

What is reduction?

Gain of electrons.

What does OILRIG stand for?

Oxidation Is Loss, Reduction Is Gain.

What is oxidation state?

A number showing the effective charge of an atom in a compound or ion.

What is relative atomic mass?

The weighted average mass of an element’s isotopes.

How do you calculate relative atomic mass from isotope abundance?

Sum of (isotope mass × abundance) ÷ total abundance.

What is Avogadro’s constant?

6.02 × 10^23 particles per mole.

What is 1 mole?

6.02 × 10^23 particles.

What is molar mass?

The mass of 1 mole of a substance in g mol^-1.

What is the formula for moles from mass?

n = m / M

What is the formula for mass from moles?

m = nM

How do you convert moles to particles?

Multiply by 6.02 × 10^23.

How do you convert particles to moles?

Divide by 6.02 × 10^23.

Why is Avogadro’s number useful?

It links the number of particles to the amount of substance in moles.

What is electron configuration?

The arrangement of electrons in shells or orbitals.

What is the shell electron configuration of sodium?

2,8,1

What is the shell electron configuration of magnesium?

2,8,2

What is the shell electron configuration of chlorine?

2,8,7

What is the shell electron configuration of Na+?

2,8

What is the shell electron configuration of Mg2+?

2,8

What is the shell electron configuration of Cl-?

2,8,8

What is a full electronic configuration?

The arrangement of electrons in sublevels such as 1s, 2s, 2p, 3s, 3p.

What is the full electronic configuration of sodium?

1s2 2s2 2p6 3s1

What is the full electronic configuration of magnesium?

1s2 2s2 2p6 3s2

What is the full electronic configuration of chlorine?

1s2 2s2 2p6 3s2 3p5

What is the full electronic configuration of Na+?

1s2 2s2 2p6

What is the full electronic configuration of Mg2+?

1s2 2s2 2p6

What is the full electronic configuration of Cl-?

1s2 2s2 2p6 3s2 3p6

What is an orbital?

A region around the nucleus where there is a high probability of finding an electron.

How many electrons can one orbital hold?

2

What shape is an s orbital?

Spherical.

What shape are p orbitals?

Dumb-bell shaped.

How many p orbitals are there?

3

What are the three p orbitals called?

px, py, and pz.

Do orbitals in the same sublevel have the same energy?

Yes.

What do orbital box diagrams show?

How electrons are arranged in orbitals.

How are electrons shown in orbital box diagrams?

As arrows in boxes.

What does one arrow in a box mean?

One electron in that orbital.

What do two opposite arrows in one box mean?

Two paired electrons in one orbital.

What should a dot-and-cross diagram for a covalent bond show?

Shared pairs of electrons and the outer electrons from each atom.

What should a dot-and-cross diagram for an ionic bond show?

Electron transfer, full outer shells, brackets, and charges.

Why do atoms bond?

To get a full outer shell and become more stable.

What is a word equation?

An equation written using names of reactants and products.

What is a symbol equation?

An equation written using chemical formulas and symbols.

Why do equations need balancing?

Because atoms are conserved in chemical reactions.

What must be equal on both sides of a balanced equation?

The number of each type of atom.

How do you convert a word equation to a symbol equation?

Write correct formulas for each substance, then balance the equation.

What is the ideal gas equation?

pV = nRT

What does p stand for in the gas equation?

Pressure.

What does V stand for in the gas equation?

Volume.

What does n stand for in the gas equation?

Number of moles.

What does T stand for in the gas equation?

Temperature in kelvin.

What does R stand for in the gas equation?

The gas constant.

How do you convert Celsius to kelvin?

K = °C + 273

Why must temperature be in kelvin in gas questions?

Because gas equations use absolute temperature.

What is limiting reactant?

The reactant that is used up first and stops the reaction.

What is excess reactant?

The reactant left over after the reaction finishes.

How do you identify the limiting reactant?

Compare the moles of reactants with the mole ratio in the balanced equation.

How do you calculate excess reactant left over?

Find how much reacted using the mole ratio, then subtract from the starting amount.

What is percentage yield?

(actual yield ÷ theoretical yield) × 100

Why is actual yield often lower than theoretical yield?

Product can be lost, the reaction may be incomplete, or side reactions may occur.

What is the four-step method for stoichiometry?

Balance the equation, convert to moles, use the mole ratio, convert to the required unit.

What is the product in a chemical reaction?

The substance formed.

What might make a product not environmentally friendly?

It may be toxic, polluting, persistent, non-biodegradable, or harmful to ecosystems.

What is a displacement reaction?

A reaction where a more reactive metal displaces a less reactive metal from its compound.

What rule predicts whether displacement will happen?

A more reactive metal displaces a less reactive metal from its salt solution.

Why is there no reaction in some metal + salt experiments?

The metal added is less reactive than the metal ion in the salt solution.

How do you identify the product of a displacement reaction?

The more reactive metal forms the new salt, and the less reactive metal is displaced as the element.

What remains in solution after a displacement reaction?

The salt containing the more reactive metal ion.

What solid may form in a displacement reaction?

The less reactive metal.

What observation can show displacement has happened?

A color change, a metal deposit forming, or the original metal dissolving.

What does blue copper sulfate turning colorless suggest?

Copper ions have been removed and replaced by another metal ion such as magnesium or zinc.

What happens when magnesium is added to copper sulfate solution?

Magnesium displaces copper to form magnesium sulfate and copper.

What is the equation for magnesium and copper sulfate?

Mg + CuSO4 -> MgSO4 + Cu

Why is aluminium described as apparently unreactive?

Because it has a protective oxide layer.

What is the oxide layer on aluminium?

A thin layer of aluminium oxide, Al2O3.

How does the oxide layer affect aluminium’s reactivity?

It prevents further reaction with water and dilute acids.

How can you improve a displacement experiment?

Repeat trials, keep concentrations and volumes the same, keep metal sizes equal, measure carefully, and calculate a mean.

What makes an experiment more reliable?

Repeats and averaging.

What makes an experiment more accurate?

More precise measurements and less error.