What are the similarities between molecules and elements

1 answer:

7 0

A molecule is formed when two or more atoms join together chemically. A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds.

Molecular hydrogen (H2), molecular oxygen (O2) and molecular nitrogen (N2) are not compounds because each is composed of a single element. Water (H2O), carbon dioxide (CO2) and methane (CH4) are compounds because each is made from more than one element. The smallest bit of each of these substances would be referred to as a molecule. For example, a single molecule of molecular hydrogen is made from two atoms of hydrogen while a single molecule of water is made from two atoms of hydrogen and one atom of oxygen.

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True or false, cilia and mucus help keep our lungs clean and healthy?

fiasKO [112]

Answer:

It does. They trap particles so they don’t enter.

Explanation:

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What salt is produced in each of the following neutralization reactions?

Pavlova-9 [17]

1. Salt is KNO₃

This is a strong acid - strong base reaction. HNO₃ is the strong acid and KOH is the strong base. 

H⁺ in the HNO₃ and OH⁻ of the KOH pair up and make H₂O(l). 

NO₃⁻ and K⁺ pair up to make KNO₃ salt. 

When writing chemical formulas positive ion comes first and second is negative ion. The charges should be switched. Since positive ion has +1 and negative ion has -1 after the switching off charges the product should be KNO₃.

Balance equation is 
HNO₃(aq) + KOH(aq) → H₂O(l) + KNO₃(aq)

2. Salt is Ca(NO₃)₂

This is a strong acid - strong base reaction. HNO₃ is the strong acid and Ca(OH)₂ is the strong base. 

H⁺ in the HNO₃ and OH⁻ of the Ca(OH)₂ pair up and make H₂O(l). 

Ca²⁺ and NO₃⁻ pair up to make Ca(NO₃)₂ salt. 

Positive ion is Ca²⁺ which has +2 charge and negative ion is NO₃⁻ which has -1 charge. From switching the charges Ca²⁺ gets 1 while NO₃⁻ gets 2. Hence, the salt should be Ca(NO₃)₂.

Balanced equation is
2HNO₃(aq) + Ca(OH)₂(aq) → 2H₂O(l) + Ca(NO₃)₂(aq)

3. Salt is CaCl₂

This is a strong acid - strong base reaction. HCl is the strong acid and Ca(OH)₂ is the strong base. 

H⁺ in the HCl and OH⁻ of the Ca(OH)₂ pair up and make H₂O(l). 

Ca²⁺ and Cl⁻ pair up to make CaCl₂ salt. 

Positive ion is Ca²⁺ which has +2 charge and negative ion is Cl⁻ which has -1 charge. By switching the charges Ca²⁺ gets 1 while NO₃⁻ gets 2. Hence, the salt should be CaCl₂.

Balance equation is
2HCl(aq) + Ca(OH)₂(aq) → 2H₂O(l) + CaCl₂(aq)

4. Salt is KCl

This is a strong acid - strong base reaction. HCl is the strong acid and KOH is the strong base. 

H⁺ in the HCl and OH⁻ of the KOH pair up and make H₂O(l). 

K⁺ and Cl⁻ pair up to make KCl salt. 

Positive ion is K⁺ which has +1 charge and negative ion is Cl⁻ which has -1 charge. By switching the charges K⁺ gets 1 and Cl⁻ also gets 1. Hence, the salt should be KCl.

Balance equation is
HCl(aq) + KOH(aq) → H₂O(l) + KCl(aq)

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How does volvox differ from other protists

Dovator [93]

It differs because it is a unicellular plant. Many scientists claim that Volvoxes are protists while many claim that they are plants, and protists are not plants.

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How does water affect the growth of a plant?

irina1246 [14]

Answer:

Water transports important nutrients throughout the plant.

Explanation:

Much like blood in an animal, water is necessary for a plants survival, as it transports important nutrients from the soil all through the plant's stems and leaves.

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Arrange the following atoms in order of increasing first ionization energy: He, Be, Se, Ne

Alex17521 [72]

Answer:

Be (899 kj/mol) , Se (940.9 kj/mol), Ne(2081 kj/mol), He (2370 kj/mol),

Explanation:

For noble gases as they have complete octet so they require high amount of energy to remove the electron.

Trend along period:

As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.

Trend along group:

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As the size of atom increases the ionization energy from top to bottom also decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.

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