Module 2- Teachers Flashcards
What do chemists call the forces which hold atoms together?
Bonds
What happens to outer electrons in a covalent bond?
There shared between two nuclei
What the definition of a covalent bond
The electrostatic attraction if two positive nuclei for a shared pair of electrons
What type of elements join together by covalent bonding?
Non-metal elements
How many atoms make up a diatomic molecule?
Two atoms
Name the 7 diatomic molecules?
Hydrogen, nitrogen, fluorine, oxygen, iodine, chlorine, bromine
Name the two types of covalent compounds?
Covalent network
Covalent molecule
State the definition of a molecule
A group of non-metal atoms joined together
Is the nucleus of an atom positively or negatively charged?
It has a positive charge
What charge do electrons have
Electrons are negatively charged
Give the names (and charges) of the subatomic particles present in atoms.
protons (positive), neutrons (neutral) and electrons (negative)
Why is an atom neutral ?
It is neutral because the number of protons (or positive charge on nucleus)
= number of electrons (or negative charges).
State the location and charge on a proton, neutron and electron.
Proton - one positive (in nucleus)
Electron - one negative (outside nucleus)
Neutron - neutral (in nucleus)
What is the atomic number of an atom?
The atomic number is the number of protons in the nucleus of an atom.
What is meant by the mass number?
This is the number of protons + neutrons in the nucleus of an atom.
Can you state what is meant by the term isotope ?
Same atomic number or number of protons
Different mass number or number of neutrons
What is meant by relative atomic mass?
This is the average mass of an element taking into account the number and proportions of each isotope
How are electrons arranged in an atom?
Electrons are arranged in energy levels. There are 2 electrons in the 1st energy level or 8 in the 2nd energy level
How many protons, electrons and neutrons in 23Na ?
11 protons
11 electrons
12 neutrons
What type of elements are conductors of electricity?
Metals elements and carbon
Do covalent compounds conduct electricity?
No. The do not conduct electricity as there are no charged particles which are free to move.
Why do atoms react together?
Atoms form bonds to reach a stale electron arrangement
In which state do metals conduct
Solid, molten or dissolved in water
What kind of bonding is present between non-metal atoms ?
Covalent bonding
When do covalent compounds conduct electricity?
Never. They do not conduct electricity
What kind of bonding is present between metals and non-metal elements when they combine?
Ionic bonding
When do ionic compounds conduct electricity and why?
Ionic compound only conduct either in a molten state or when dissolved in water as
IONS CAN MOVE
Why do covalent networks have very high melting points?
Covalent networks have very high melting points as lots of strong covalent bonds have to be broken which needs lots of energy
Explain why covalent molecules have low melting points?
Covalent molecules have low melting points as there are weak forces of attraction between the molecules
What is meant by electrolysis ?
The process of breaking up an ionic compound by means of electricity to form its element
What is an ion?
It’s an atom that has lost or gained an electron
What kind of compounds are liquids and gases at room temperature?
Covalent compounds
During electrolysis what happens to each electrode?
In electrolysis of an ionic compound the positive metal ions move to the negative electrode. The negative non-metal ions move to the positive electrode.
Definition of a metallic bond?
Metallic bonding is the electrostatic attraction between positively charges ions and delocalised electrons.
Why does d.c. have to be used in electrolysis
A d.c. source is used to keep a constant positive and negative electrode and allow the products to be identified
Definition of an ionic bond?
An ionic bond is the electrostatic attraction between positive and negative ions
Why does ionic compounds only conduct when molten or in solution and not when solid?
The ions are free to move in a molten state. They are tightly held in a lattice and the ions cannot move in a solid
How would you describe the melting point of ionic compounds
Ionic compounds have high melting points as it takes a lot of energy to break the strong ionic bonds and break up the ionic lattice.
What type of structure do solid ionic compounds exist
They exist as a lattice of oppositely charged ions.
Why do metals conducts?
They have delocalised electrons
