chemistry 4.1 defining the atom

chemistry 4.1 defining the atom

Tala sahrij , Linda ramzi , Leen soufian

Early Models Of the Atom

Using your unaided eyes , you cannot see the tiny fundamental particles that make up matter . Yet , all matter is composed of such particles , which are called atoms . An atom is the smallest particle of an element that retains its identity in a chemical reaction .

Democritus's Atomic Philosophy

The ancient greek pre-socratic philosopher Democritus(460 BC- 370 BC) was among the first to suggest the existence of atoms , he is remembered today for his formulation of an atomic theory of the universe .

Daltons atomic theory

the real nature of atoms and the connection between observable changes and events at the atomic level were not established for more than 2000 years after Democritus's death . the modern process of discovery regarding atoms began with John dalton (1766-1844) , an English chemist and a schoolteacher . by using experimental methods , Dalton transformed Democritus's ideas on atoms into a scientific theory .

Daltons atomic theory

1-All elements are composed of tiny indivisible particles called atoms

2-Atoms of the same element are identical but the atoms of any one element are different from those of any other element .

3-Atoms of different elements can physically mix together or can chemically combine in simple whole -number ratios to form compounds

4- Chemical reactions occur when atoms are separated from each other , joined , or rearranged in a different combination . Atoms of one element , however , are never changed into atoms of another element as a result of a chemical reaction .

Sizing up the Atoms

Atoms of the same element have the same properties because they are all made of the same kind of atoms .

Atoms are super small that if you line up 100,000,000 copper atoms side by side they would produce a line only 1 cm long!

Despite individual atom’s small size they can still be observed using instruments such as scanning electron microscopes

Multiple Choice

John Dalton said all elements are made of tiny particles called ________

• protons

• compounds

• atoms

• molecules

Multiple Choice

the first atomic theory said atoms of different elements can chemically combine to make _______

• matter

• compounds

• volume

• atoms

Multiple Choice

All drops of mercury have the same properties .

• True

• False

Multiple Choice

Who was the first person to suggest atoms exist?

• Ms. Humphries

• John Dalton

• Rutherford

• Democritus

Multiple Choice

John dalton was a greek philosopher and the first person to suggest atoms exist

• False

• True