Pure Substance and Mixtures

Flashcards covering the classification of matter, elements, compounds, and types of mixtures based on lecture notes.

How can matter be classified according to its composition?

Matter may be classified into two categories: pure substances and mixtures.

What are the defining characteristics of a pure substance?

A pure substance has a definite or fixed composition, is made of a specific number of atoms combined through chemical reactions, and possesses definite physical and chemical properties.

What is the simplest form of matter that cannot be decomposed into simpler forms by physical or chemical means?

Elements.

Of the $118$ elements known to exist in the periodic table, how many are naturally occurring and how many are synthetic?

$94$ are naturally occurring and $24$ are synthetic.

How does the periodic table classify elements based on their position?

Metals are located on the leftmost, nonmetals on the rightmost, and metalloids on a staircase-like line between them.

Which metal is the only one that exists in liquid form at room temperature?

Mercury, also known as quicksilver.

What are the properties of metals mentioned in the lesson?

Metals are solid at room temperature (except Mercury), lustrous, malleable, ductile, and are the best conductors of heat/electricity.

What is the only nonmetal that exists in liquid form at room temperature?

Bromine.

Why are metalloids also referred to as semiconductors?

Because they conduct heat and electricity, but not as effectively as metals do.

How do the properties of elements within a compound change once the compound is formed?

The properties of the constituent elements are different from the properties of the compound formed.

In the example of table salt ($NaCl$), how do the properties of the compound differ from its elements?

Table salt is safe and edible, while its constituent elements Sodium ($Na$) and Chlorine ($Cl$) are harmful and toxic.

What is the primary difference between a mixture and a compound regarding how they are formed?

Mixtures consist of substances combined physically with no chemical reaction, whereas compounds are formed through chemical reactions in a fixed ratio.

What are the two components that make up a solution?

The solute (the substance being dissolved, existing in smaller amounts) and the solvent (the dissolving medium, which is the most abundant component).

What kind of solution is steel?

Steel is a solid solution, or an alloy, made up of iron and carbon.

How is a homogeneous mixture different from a heterogeneous mixture?

In a homogeneous mixture (solution), substances are evenly distributed and cannot be distinguished by the naked eye; in a heterogeneous mixture, substances are not evenly distributed and components can be distinguished.

What are the two classifications of heterogeneous mixtures?

Colloids and suspensions.

What is the Tyndall effect?

The phenomenon wherein light is scattered by particles.

What characterizes a colloid in terms of particle behavior?

Colloid particles are larger than those in a solution but smaller than those in a suspension; they do not settle at the bottom after standing and they exhibit the Tyndall effect.

What are two examples of colloids?

Milk and mayonnaise.

Why do particles in a suspension settle at the bottom over time?

Particles in a suspension are large enough to be seen by the naked eye and settle due to gravity.

Which beverage was provided as an example of a suspension?

Boba milk tea.