Chemistry Flashcards
How did Mendeleev contribute to the formation of the periodic table?
Mendeleev first put elements with similar properties into horizontal rows.
He then altered this and placed elements with similar properties in vertical columns.
He arranged the elements in order of increasing mass but made some exceptions so that the elements in each column behaved in a similar way.
He left gaps for elements that had not been discovered yet.
How are shells filled when drawing an atom?
A new shell can not be started until the inner shell is filled
When you place electrons in a shell the go at 12, 3, 6 and 9 O’clock
Electrons are like bus passengers they do not pair up unless they have to.
Where are electrons found in atoms?
Electrons are arranged around atoms in shells. The closer a shell is to the nucleus the lower the energy of the electrons in that shell.
What happens when a metal reacts with water?
When any metal reacts with water, the products are a metal hydroxide and hydrogen gas.
How does ionic bonding work?
Just like magnets, ionic bonding produces an electrostatic force that pulls the two oppositely charged electrons together.
Opposite Charges Attract.
What is an ionic bond?
An ionic bond is the attraction between a positively charged ion (cation) and a negatively charged ion (anion).
Electrostatic attraction between the oppositely charged ions is the force holding the ions together.
How do atoms become ions?
All atoms start of with a charge of zero
If they donate electrons they become Positively charged ions (called cations), they have more protons than electrons.
If they gain electrons they become negatively charged ions (called anions), they have more electrons than protons.
Which atoms form positive ions?
Metal atoms become positive ions/Cations
They lose electrons
e.g. Alkali, Alkaline Earth, and Group 3 metals
Which atoms form negative ions?
Non-metal Atoms become negative ions/Anions
They gain electrons
e.g. Group 5, Group 6, and Halogen non-metals
What are covalent bonds?
A covalent bond is formed when pairs of electrons are shared by several atoms and have their energies lowered as a result of this.
Stable covalent bonds are formed between many non-metallic elements since the atoms usually possess half-filled outer electron shells.
What are the properties of materials containing covalent bonds?
Covalently bonded inorganic materials have very high melting and boiling points and are hard and strong.
They are non-conductors due to the fact that their electrons are tightly bound in the bonds themselves.
What is a metallic bond?
Individual metallic atoms lose their outer valence electrons which then exist in the metal as a cloud or sea of electrons.
The bond is the electrostatic attraction between the fixed positive ion cores of the atom and the negative electron cloud.
What are the properties of materials that contain metallic bonds?
Metallic bonded materials are good conductors of heat and electricity, are opaque, lustrous (unless obscured by oxides) and are ductile due to the mobility of their electrons.
They have moderately high melting points.
What are secondary bonds?
Secondary bonds are those comparatively weak inter-molecular bonds formed as the result of dipole attractions, the dipoles forming as a result of the unbalanced distribution of electrons in molecules.
Dipoles may be permanent (hydrogen fluoride and water molecules), or they may be temporary (known as van der Waals forces).
Although weak bonds, they still play a significant part in determining the structures and properties of many non-metallic materials.
What are metal ores and why do they form?
Most metals are reactive and are found as compounds because they react with substances around them.
Rocks that contain these metal compounds are called ores
