All categories

2 years ago

How many metals are on the periodic table?

Chemistry

2 answers:

sergey [27]2 years ago

7 0

There are 91 metals on the periodic table.

Setler79 [48]2 years ago

3 0

There are 88 metals. Hope this helps!

You might be interested in

Match the following associations. Exothermic or endothermic

Alekssandra [29.7K]

Answer:

1) ∆H is positive $\Rightarrow$ Endothermic

2) $E_p>E_r$ $\Rightarrow$ Endothermic

3) Energy is absorbed $\Rightarrow$ Endothermic

4) $E_r>E_p$ $\Rightarrow$ Exothermic

5) ∆H is negtive $\Rightarrow$ Exothermic

Explanation:

∆H is called as enthalpy change

It is also called as Heat of reaction

Energy is required for the bond to break a bond.

Energy is released when a bond is formed.

$H_2+Cl_2>2HCl$

that is

$H-H+Cl-Cl>2H-Cl$

We see in this equation, bonds between hydrogen and chlorine molecules gets broken and on the right side bond is formed in HCl.

If energy of products greater than energy of reactants then the reaction enthalpy change is endothermic .

If energy of products lesser than energy of reactants then the reaction enthalpy change is exothermic .

For example

$\Delta H=E_p-E_r$

$=30KJ-20KJ$

$=+10KJ$

(positive hence endothermic)

$\Delta H=E_p-E_r$

$=10KJ-40KJ$

$=-30KJ$

(negative hence exothermic)

8 0

3 years ago

When a 5.00-g metal piece, A, was immersed in 38.0 mL of water, the water level rose to 50.0 mL. Similarly, when a 5.00-g metal

Mnenie [13.5K]

Answer:

A is denser than B as it's volume for the same mass is smaller.

Explanation:

Hello.

In this case, we first need to take into account that the density of each metal A and B is computed by dividing the mass over the volume of each metal which is actually computed by substracting the volume of water from the volume of the water and the solid:

$V_A=50.0mL-38.0mL=12.0mL\\\\V_B=60.0mL-38.0mL=22.0mL$

Next, we compute the densities as shown below:

$\rho_A=\frac{m_A}{V_A}=\frac{5.00g}{12.0mL}=0.42g/mL\\ \\\rho_B=\frac{m_B}{V_B}=\frac{5.00g}{22.0mL}=0.23g/mL$

In such a way, A is denser is B as it's volume for the same mass is smaller.

Best regards.

4 0

2 years ago

How many Helium atoms are in 12 grams of Helium?

horsena [70]

12gHe/1 × 1molHe/4.0026g × 6.02x10^23atomHe/1mol = 1.8 atoms

6 0

3 years ago

I. Choose the letter of the correct answer. Write your answer on a separate sheet of paper.

omeli [17]

Answer:

,,,

Explanation:

6 0

2 years ago

7.66 Write balanced equations for the following reactions: (a) potassium oxide with water, (b) diphosphorus trioxide with water,

White raven [17]

Explanation:

(a) potassium oxide with water

$K_2O(s)+H_2O(l)\rightarrow 2KOH(aq)$

According to reaction,1 mole of potassium oxide reacts with 1 mole of water to give 1 mole of potassium hydroxide.

(b) diphosphorus trioxide with water

$P_2O_3(s)+3H_2O(l)\rightarrow 2H_3PO_3(aq)$

According to reaction,1 mole of diphosphorus trioxide reacts with 2 moles of water to give 2 moles of phosphorus acid.

(c) chromium(III) oxide with dilute hydrochloric acid,

$Cr_2O_3(s)+6HCl(aq)\rightarrow 2CrCl_3(aq)+3H_2O(l)$

According to reaction,1 mole of chromium(III) oxide reacts with 6 moles of hydrochloric acid to give 2 moles of chromium(III) chloride and 3 moles of water.

(d) selenium dioxide with aqueous potassium hydroxide

$SeO_2 (s)+2KOH (aq)\rightarrow K_2SeO_3(aq)+H_2O(l)$

According to reaction,1 mole of selenium dioxide reacts with 2 moles of potassium hydroxide to give 1 mole of potassium selenite and 1 mole of water.

6 0

3 years ago