science (C1 and C2) - end of year

a row on a periodic table is called

period

a column on the periodic table is called

group

proton - location, relative mass and relative charge

nucleus, 1, +1

neutron - location, relative mass, relative charge

nucleus, 1, 0

electron - location, relative mass, relative charge

shells, 1/2000th, -1

what did the gold foil experiment show?

1. Most of the atom is empty space – because most alpha particles passed straight through the gold foil without being deflected.

2. The atom has a small, dense, positively charged nucleus – since a few alpha particles were deflected at large angles, or even bounced back, indicating they hit something dense and positively charged at the centre

using electronic structure, how can you tell which period an element is in?

Count the number of electron shells (energy levels). That number = the period the element is in.

using electronic structure, how can you tell which group an element is is?

Look at the number of electrons in the outer shell.

That number = the group number (for Groups 1–7).

If it’s full (8 electrons), it’s in Group 0 (noble gases).

ion

An atom or molecule that has gained or lost electrons, giving it a positive or negative charge.

relative atomic mass number

The average mass of all the isotopes of an element,

weighted by their abundance, compared to carbon-12. - the big number

when balancing an equation, what do you NEVER change?

You never change the small numbers in a formula. Only change the big numbers in front

describe the reactivity of group 1 metal and water

It reacts to form a metal hydroxide and hydrogen gas. The reaction gets more violent down the group.

the 4 state symbols and their names

s - solid

g - gas

l - liquid

aq - Aqueous (dissolved in water)

describe the reactivity of group 7 elements

Reactivity decreases as you go down.

The atoms get larger and gain electrons less easily.

describe the reactivity of group 0 elements (use electronic structure)

Group 0 elements have a full outer electron shell (complete valence shell). This stable electronic structure makes them very unreactive because they have little tendency to gain, lose, or share electrons.

compound

A compound is a substance made of two or more elements chemically joined together.

mixture

a substance made up of two or more elements/compounds that are not bonded together

relative charge of proton

+1

relative charge of neutron

0 (no charge)

relative charge of electron

-1

describe the melting point for the elements in group 7 of the periodic table

Increases down the group

describe the boiling point for the elements in group 7 of the periodic table

increases down the group

describe the molecular mass for the elements in group 7 of the periodic table

Increases down the group (atoms get heavier)

describe the reactivity for the elements in group 7 of the periodic table

Decreases down the group (harder to gain an electron)

describe a physical process that could be used to separate a mixture of an insoluble solid and water

Filtration is the physical process used.

The mixture is poured through filter paper: The solid stays on the paper (residue). The water passes through (filtrate).

name a physical process that could be used to separate a mixture of a soluble solid and water

Evaporation – Heat the mixture so the water evaporates, leaving the solid behind (e.g. salt from salt water).

Who proposed the Plum Pudding Model of the atom? What was it, and what evidence led to it?

Scientist: J.J. Thomson (1904)

Model: Atom is a sphere of positive charge with negatively charged electrons embedded in it (like plums in a pudding)

Evidence: Discovery of the electron (1897) using cathode ray experiments, showing atoms contain small, negatively charged particles.

Who proposed the Nuclear Model of the atom? What was it, and what evidence led to it?

Scientist: Ernest Rutherford (1911)

Model: Atom has a small, dense, positively charged nucleus at the center, with electrons orbiting around it. Most of the atom is empty space.

Evidence: Gold foil experiment — most alpha particles passed through, but some were deflected at large angles, indicating a dense central nucleus.

describe two problems with walt versions of the periodic table and how did mendeleev overcome these problems?

Problems with early periodic tables:

1. Elements didn’t always fit in order of atomic mass (e.g., iodine and tellurium didn’t align properly).

2. Some elements were missing, leaving gaps.

How Mendeleev fixed this:

• He arranged elements by similar chemical properties, not just atomic mass.

• He left gaps for undiscovered elements and predicted their properties, which were later confirmed.