Atom structure

When was the first idea of atom found?

The nucleus of an atom is located at the centre.

Choose the correct answers about the electron cloud:

All atoms have the same [blank_start]internal[blank_end] structure made up of: the [blank_start]nucleus[blank_end], very [blank_start]smalll[blank_end] compared to the size of the atom and the [blank_start]electron[blank_end] [blank_start]cloud[blank_end], the external area of the atom which is much larger than the [blank_start]nucleus[blank_end].

The Atomic Theory was admitted in 1904.

Dalton in [blank_start]1808[blank_end] said that atoms of the same [blank_start]elements[blank_end] had identical properties and those of [blank_start]different[blank_end] elements are different. [blank_start]Thomson[blank_end] in 1904, designed an atomic model where [blank_start]electrons[blank_end] were incrusted in a [blank_start]positive[blank_end] sphere. Rutherford in [blank_start]1911[blank_end] drew an atomic model were the nucleus had got almost all the [blank_start]mass[blank_end] of the atom and all the [blank_start]positive[blank_end] charge, and he added [blank_start]electrons[blank_end] in an electron cloud where it was located the [blank_start]negative[blank_end] charge. In 1913 [blank_start]Bohr[blank_end] specified the [blank_start]orbits[blank_end] in the electron cloud and he detailed how [blank_start]electrons[blank_end] moved in them.

Marie Curie was born in Russia

At the beginning of the 19th century 75 chemical elements were known.

What is represented by every letter?

Choose the correct staments about atoms and numbers:

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Describe correctly this atom

The periodic table contains [blank_start]118[blank_end] elements ordered by their [blank_start]atomic[blank_end] number. The system is divided into: - [blank_start]seven[blank_end] rows called [blank_start]periods[blank_end] - [blank_start]eighteen[blank_end] columns, called [blank_start]groups[blank_end] or families. Elements which belong to the same group have got [blank_start]similar[blank_end] chemical properties. We can distinguish four general types of elements: - [blank_start]Metals[blank_end]: They are electricity and heat conducted. They are in [blank_start]solid[blank_end] state except Mercury. - Semimetals: Their behaviour is [blank_start]metallic[blank_end] or [blank_start]non metallic[blank_end] depending on the conditions. - [blank_start]Non-metals[blank_end]: They are heat and electricity bad conducted. They are in solid, gas and liquid state. - [blank_start]Noble gases[blank_end]: They do not combine with other chemical elements.