Science Study Guide 3

Elements that have the same number of valence electrons are

within the same group of the periodic table

Ca, Ar, Na, N, O, Cl (use a periodic table) 1: Which of these elements can become stable by losing 1 electron? 2: Which of these elements is least likely to react with other elements?

1: Sodium because elements are only stable because it only has to lose one valence electron to get to zero 2: Argon because it has eight valence electrons

How many sodium ions are needed to balance the charge of one phosphate ion? (Na1+ and PO₄³⁻)

3

A carbon can form four covalent bonds. How many valence electrons does carbon have?

4

When atoms react, they form a chemical bond, which is defined as

A force of attraction that holds atoms togetheras a result of the rearrangement of electrons between them

Identify each molecule below as either a polar molecule or a non polar molecule. Explain. (CO2 and O2)

Carbon dioxide is non-polar because of the symmetry of its bonding. Oxygen is non-polar because they are the same element and they equally share the 4 electrons

When an atom loses or gains electrons it becomes an

Ion

A potassium atom has 19 protons. A potassium ion has the charge of 1+. How many electrons does a potassium ion have? Explain.

A potassium ion has 18 electrons because if the charge is 1+ then you would need to lose a electron to become positive.

Based on the data which compounds do you think are ionic compounds? Molecular compounds? Explain (Magnesium Chloride MgCl2) (Methane CH4) (Zinc Chloride ZnCl2)

Magnesium Chloride is a ionic compound because it is between a non metal and a metal and they give electrons instead of sharing. Methane is a molecular compound due to both elements being non metals. Zinc Chloride is a ionic compound due to the elements in the compound being non metal and metal.

(Magnesium, Neon, Sulfur, Aluminium, Potassium, Fluorine) Predict the formula of the compounds, if any that would form from each of the following combinations of elements: magnesium and fluorine, aluminum and sulfur, and potassium and neon. If a compound is unlikely to form explain the reason why.

Magnesium fluoride (MgF2) is the formula because Mg has two valence electrons and fluoride has 7 so MgF2 is the formula. Aluminum Sulfide (Al2S3) this is the formula because Al has 3 valence electrons and sulfur 6 valence electrons. The two aluminum has 6 valence electrons in total so they can give two to each of the sulfur atoms making it an ionic bond. Potassium and Neon do not bond since neon is one of the noble gases having its outer shell completely filled making there no need to bond.

A covalent bond in which electrons are shared equally is called a

Non-polar bond

Magnesium Chloride is an example of an ionic compound, which is a compound composed of

Positive and negative ions

Based on their chemical formulas, which of these compounds is not likely to be an ionic compound: KBr, SO2, or AlCl3? Explain.

SO2 is not a ionic compound because Sulfur and Oxygen are two non metals making it a covalent bond

If an ice cube and a scoop of table salt are left outside on a warm, sunny day, why does the ice cube melts and the salt doesn't

The melting point of salt is around 800̊̊̊̊̊̊̚℃, whereas water is 0℃.

The chemical formula for a glucose molecule is C6H12O6. The subscripts represent the:

The total number of bonds made by each atom

An electron dot diagram shows an atom's number of

Valence electrons

when a atom loses an electron it becomes..

a positive ion