upload your written notes and/or picture/photos of your notes in 13.1 & 13.2

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3A36 and 3A37

13.1: matters are made up of atoms.....

13.2In the modern Period Table,elements are arranged in order of increasing the number of atomic number

group 0 elements are noble gases

the reactivity of group i and ii elements is increased down the group

group vii elements’ reactivity is decreased down the group

different atoms have different size and mass

the number of protons and electrons are the same

protons and neutrons are placed inside the nucleus

group i elements react with water to form hydrogen

group ii elements react with dilute hydrochloric acid to form hydrogen

group vii elements react with metal to form salts

Element contain one kind of atoms only

Mass number = the number of neutrons and protons

13.2

In modern periodic table

Horizontal rows are called period

Vertical columns are called groups

Some elements exist as molecules

Different elements have different sizes and masses

Elements classified into metals,semi metals and non-metals

Proton(+) and neutron are located in the nucleus of an atom.

Electron(-)move fast around the nucleus

In an atom,the number of protons is the same as the number of electrons.

Atomic number=protons

Mass number=protons+neutron

Cation(+),anion(-)

13.1

Element:one kind of atoms only

Physical properties of metal:

Shiny/good electrical conductor/ductile/malleable…

Non-metal:

Dull/brittle/low melting point…

Proton&Neutron:in the nucleus

Electron:around the nucleus

Relative mass:

P&N:1

E:0.0005

Relative charge:

P:+1

N:0

E:-1

Atomic number=P

Mass number=P+N

Loses=()+

Gains=()-

13.2

7 periods&8 groups(I to 0)

Same group have similar chemical properties but different reactivity