🧪 | Unit 3 | Structure & Bonding Flashcards
Properties of metals
∘ lustrous ∘ high m.p. ∘ high densities ∘ malleable + ductile ∘ conduct electricity + heat ∘ lose electrons - form cations ∘ form basic oxides
Properties of non-metals
∘ non-reflective ∘ low m.p. ∘ low densities ∘ brittle, delicate in solid state ∘ do not conduct electricity or conduct heat
∘ gain electrons - form anions
∘ form acidic oxides
∘ non-metals bond to form covalent compounds
Lattice
A regular arrangement of alternating positive and negative ions.
What is the proton number?
The proton number is the number of protons in the nucleus of an atom.
What is the nucleon number?
The nucleon number is the total number of protons and neutrons in the nucleus of the atom.
Properties of covalent compounds
- have low m.p. and b.p.
- liquids and gases at room temperature
- volatile
- not water-soluble
- can’t conduct electricity
Properties of ionic compounds
- high m.p. and b.p.
- solid at room temperature
- not volatile
- water-soluble
- conduct electricity in molten state or in aqueous solution
- brittle
How are covalent compounds formed?
Covalent compounds are formed when electrons are shared between non-metal atoms to have full valence shells.
How are ionic compounds formed?
Ionic compounds are formed when electrons are transferred from one atom to another to have a full valence shell.
What are ionic bonds?
Ionic bonds are electrostatic forces of attraction between opposite charges.
What is an ion?
An ion is an electrically charged atom formed by the loss or gain of electrons.
What is an alloy?
An alloy is a mixture of a metal with other elements.
Define isotope
Isotopes are atoms of the same element that have the same proton number but different nucleon numbers.
Why do isotopes still have the same properties?
Isotopes still have the same properties because they have the same number of valence electrons.
What is an atom?
An atom is the smallest particle of a substance that can exist.
What is an element?
An element is a substance that is made up of the same type of atom and cannot be split into anything further.
What is a compound?
A compound is a pure substance made up of two or more elements that are chemically bonded.
What is a mixture?
A mixture is a combination of 2 or more substances that are not chemically bonded.
What is a pure substance?
A substance that contains only one element is a pure substance.
What is a molecule?
Two or more atoms bonded together is a molecule.
Can be same or different elements.
Structure of an atom
- electron shells with electrons
- nucleus: protons and neutrons
Mass of a proton
1 amu
Mass of a neutron
1 amu
Mass of an electron
1/1836 amu
Charge of a proton
+1
Charge of a neutron
No charge
Charge of an electron
-1
What is
atomic number?
The number of protons in the nucleus of an atom is the atomic number.
What is
mass number?
The total number of neutrons and protons in the nucleus of an atom is the mass number.
What is an isotope?
An isotope is a atom of the same element with the same number of protons but different number of neutrons.
How to draw an ion?
With the ions of each element in those box-brackets, include the charge.
Ionic bonds are formed between what types of elements?
Ionic bonds are formed between metallic and non-metallic elements
Properties of diamond
- giant tetrahedral structure (each C atom bonded to 4 other C)
- many strong covalent bonds that require a lot of energy to break
- does not conduct electricity
- has a very high melting point
- is extremely hard and dense
Allotrope
Different forms of the same element
Properties of graphite
∘ each C atom is bonded to 3 other C atoms
∘ has a slightly lower m.p. than diamond
∘ many strong covalent bonds that require a lot of energy to break
∘ slippery
∘ soft
∘ layers with weak intermolecular forces between the electrons
∘ can conduct electricity: there is a delocalized electron for each carbon atom
Properties of silicon dioxide
∘ each Si atom bonds to 4 oxygen atoms
∘ each oxygen atom bonds to 2 Si atoms
∘ giant, tetrahedral structure
∘ very hard
∘ high density and boiling point
∘ insoluble in water
∘ can’t conduct electricity
What is a covalent bond?
The electrostatic attraction between a positive nucleus and a shared pair of electrons
Simple molecular substances have low m.p.
Why?
They have weak intermolecular forces which are easy to break.
What is metallic bonding?
Metallic bonding is a lattice of positive ions in a “sea” of electrons.
Why can metals conduct electricity?
The sea of electrons are delocalized electrons, meaning that they are able to move and carry charge.
Why do metals have high m.p.?
They have strong metallic bonds.
What is a metallic bond?
The electrostatic attraction between a positive metal ion and the sea of delocalized electrons.
Why can metals conduct heat?
The delocalized electrons can pass on thermal energy.
Why are metals malleable and ductile?
The layers of positive ions can slide over each other.
Why are alloys harder than pure metals?
Alloys are of different metals, which means the positive ions are in different sizes. This doesn’t allow the layers of positive ions to slide over each other.
Why are ionic compounds water-soluble?
Both ionic compounds and water are polar.
Why are ionic compounds brittle?
When the ionic compound is hit, the layers of ions in the lattice slide over each other, causing ions of the same charge to slide next to each other and repel.
