grade 9 chemistry

_________ nuclear atomic model describes the atom as mostly empty space. Its mass is concentrated in the nucleus that consist of protons and neutrons. However it could not explain the chemical properties of elements.

• Rutherford

• Dalton

• Bohr

• Democritus

_____ atomic model describes the atom like a solar system, where the electron is found only in specific circular paths, or orbits, around the nucleus.

• Rutherford

• Dalton

• Bohr

• Thompson

_______ formulated a mathematical equation that describes the behavior of the electron. The solution to the equation is used to calculate the probability of finding the electron at a particular region in space around the nucleus.

• Scrodinger

• Thompson

• Rutherford

• Bohr

The ____________ are the outermost electrons which are directly involved in chemical bonding.

• protons

• valence electrons

• covalent

• non metals

An covalent bond involves complete transfer of electrons, thus ions are formed. It involves metals with low electronegativity and non-metals with high electronegativity

• true

• false

A covalent bond involves the sharing of electrons that results in the formation of covalent compound whose representative particle is a molecule. As a whole, a molecule does not carry a charge

• true

• false

Covalent bonds can may be polar or non polar

• true

• false

What is the period number of an element with an atomic number of 15 (Phosphorus)?

• 1

• 2

• 3

• 4

Which of the following elements is a noble gas?

• O

• N

• He

• Cl

In a Lewis dot structure, what do pairs of dots represent?

• Valence electrons that will always form bonds

• Inner-shell electrons

• Lone pairs or bonding pairs of electrons

• Protons in the nucleus