Chemistry Flashcards
(32 cards)
What is the atomic number?
The number of protons
What is the atomic mass?
The number of protons+neutrons
What are periods?
The rows (7)
What are groups?
The columns (18)
How do you determine the number of electrons?
In a neutral atom, the number of protons = the number of electrons
What does every atom want to do?
Wants to be stable - have all a full valence shell
Non-metals try to?
Gain electrons, become anions
Metals try to?
Lose electrons, become cations
Electron configuration of stable atoms (1-20)
2,8,8,2
What do the groups determine?
The number of valence ELECTRONS
What do periods determine?
The number of electron SHELLS
Periodic table trends: Atomic Radius
(from nucleus to valence shell) increases going down groups and decreases going left to right on a period. F is the largest, He is the smallest.
Periodic table trends: Metal characteristics
Metallic characteristics decrease as you move from left to right across the periods. This is because the atoms want to accept and gain electrons instead of lose. Increases going down to F, decreases going to He.
Periodic table trends: Electron Affinity
The amount of energy required to gain an electron. Higher electron affinity means the atom accepts the electron easier - non-metals have a higher electron affinity. Increases going up a group and going left to right across a period
Periodic table trends: Ionisation Energy
Amount of energy required to pull an electron away/lose an electron. Increases left to right on periods (because non-metals want to gain not lose) Decreases from top to bottom in groups. The further away the electrons are from the nucleus, the easier they are to remove, hence, the trend is opposite to that of the atomic radius
First group is?
Alkali metals
Second group is?
Alkaline Earth metals
3-12th groups are?
Transition Metals
18th group is?
Nobel Gases
Non-metals are?
groups 14-17
Group 17 is?
Halogens (F, Cl, Br, I)
What is ionic bonding?
Metal cations and Non-metal anions bond to form an ionic compound. Ionic bonding occurs when an atom gives another atoms electrons, and the overall charge of the atom is changed. This results in the two atoms bonding due to their opposite charge. It is the electrostatic attraction between oppositely charged ions. The net charge of the compound must be 0/neutral.
Properties of ionic compounds?
A lot of energy is required to move ions out of their positioning, meaning they are hard to melt. At room temp they form hard brittle crystals. An example of this is Sodium Chloride (salt)
What is covalent bonding?
When two non-metals bond together, they both need full valence shells to remain stable, so they share their shells. The sharing of pairs of electrons is called covalent bonding.
