Chemistry

Question 1

Atomic Structure

Answer 1

-Protons and nucleus in the centre/core. Atomic core.
-Electrons orbit in shells.

Protons (+) Neutrons (O) Electrons (-)

Question 2

Symbols, AM and AN.

Answer 2

-Atomic Number - Protons
-Atomic Mass - Protons + Neutrons

24^Mg - AN
12V -AM

Stable atom means electrons = protons.

Formula to find neutrons = AM - AN.

Question 3

Electron Shells

Answer 3

1st: 2
2nd: 8. ->
3rd: 8. -> 8/18
4th: 8. -> 32 (Can be 8/18)
5th: 8/18
6h: 8

Question 4

Groups and Periods

Answer 4

Groups V.
Match number of valence electrons as you go down.

Periods >
The number of electrons grow by 1 further and further and have same number of electron shells.

Question 5

Stable Atoms

Answer 5

-Have full 8 electrons in outermost shell - otherwise known as valence electrons.

Question 6

Unstable Atoms

Answer 6

-Will lose/gain electrons to become stable turning into an isotope.
-Those with less valence electrons I.E Li. Are more reactive.

Question 7

Valence Electrons

Answer 7

-Electrons in outermost shell.
-Most important as they determine their reaction with other atoms. (Reactivity)
-Determines properties.

Question 8

Chemical Equations

Answer 8

Reactants -> Products

E.g
-Zinc + hydrochloric acid -> Zinc chloride + hydrogen.

Or

Zn + 2HCL -> ZnCl v2 + H v2

Question 9

Superscripts, subscripts and coefficients

Answer 9

Sub- Number of (Below). Zn v2
Super - Charge of ion (Above). Zn ^2

Coefficient is the normal sized number in front of atoms/compounds that tells how many.

E.g
2Hv20 = two water molecules.

Question 10

Balancing Chemical Equations

Answer 10

E.g 1

Al v2 + Fe v2 O v3 -> Al v2 Ov3 + Fe

|
v

2Al + Fe v2 + Ov3 -> Al v2 Ov3 + 2Fe

E.g 2

Pb(OH)v2 + HCl -> Hv2O + PbCl v2

|
v

1Pb(OH)v2 + 2HCl -> 2Hv2O + 1PbCl2

Question 11

Physical Change

Answer 11

-Shape/form
-Expansion/contraction
-Change of state
-Mixing substances together
-Dissolving a substance

*Often reversible - not always

Question 12

Chemical Change

Answer 12

-Change in colour
-Smelling a gas or seeing fizz/bubbles
-Seeing a new solid (precipitate) form
-Observing new energy produced as heat/light

*Often not reversible