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1

What is the relationship between an atom and an element?

An atom is a fundamental building block of matter, and an element is a pure substance that’s made of just one kind of atom

2

How are protons and neutrons different from and similar to each other?

Protons have a positive charge, while neutrons are neutral. Both protons and neutrons are located in the nucleus of an atom. Both protons and neutrons have similar mass.

3

How do electrons differ from both protons and neutrons?

Electrons are found in the relatively large region of an atom outside the nucleus. Electrons are negatively charged and have a much smaller mass than protons and neutrons.

4

How are protons, neutrons, and electrons arranged to form an atom?

Both protons and neutrons are located in the nucleus of an atom. Electrons are found in the larger region of an atom outside the nucleus.

5

What are two ways electrons can be gained or lost from an atom?

Electrons can be gained or lost from atoms 1) as bonds are formed or broken between atoms, or 2) through movements as part of an electric current.

6

How is the periodic table of the elements organized?

The periodic table organizes elements into groups and periods according to their atomic number. A group is a vertical column. A period is a horizontal row. There are currently about 115 elements on the periodic table.

7

How do scientists classify some of the elements on the periodic table?

There are 6 groups of elements that scientists identify as having similar physical and chemical properties. These are the highly reactive metals (alkali metals and alkaline earth metals), the less reactive metals (transition metals), the metalloids, the less reactive nonmetals, the highly reactive nonmetals (halogens) and the nonreactive noble gases.

8

Why is the periodic table such a useful tool for chemists?

Atoms in the same group on the periodic table tend to have similar physical and chemical properties. This is because they have the same number of electrons in their outer energy levels. Scientists can use this information to predict how atoms will react with each other. Atoms in the same period have the same number of energy levels, which also helps scientists predict how an atom will interact with other atoms.

9

What is a mixture?

A mixture is a combination of two or more substances that are able to be separated.

10

What is the difference between a mixture, a solution, and a pure substance?

A pure substance is a material with a definite chemical composition. A solution is a homogeneous mixture. It is the same throughout the mixture. A mixture is any combination of two or more substances that can be separated.

11

What is diffusion, suspension, and colloid?

A diffusion is a dispersion of a substance in a gas or a liquid. A suspension is a fluid that has solid particles floating in it. A colloid is a mixture where microscopic particles are evenly spread out within a medium. Colloids can be solids, liquids, or gases. A Colloid is a Heterogeneous mixture.

12

What are some different ways mixtures can be separated?

Mixtures can be separated in many ways. Mixtures can be physically separated through picking out individual items. Mixtures can also be separated through filtration. Magnets are sometimes used to separate metals. Solutions can be separated by distillation.

13

What is a compound?

A compound is a pure substance made of atoms of two or more elements chemically bonded together. A compound’s chemical and physical properties are different from the properties of the elements from which it is made.

14

How are compounds named?

Compounds often have two or more names: 1. chemical names that are derived from the elements that make them up, and 2. common names that are different from the chemical names.

15

How are compounds made from carbon unique?

A carbon atom can bond to four other atoms. Because of this, millions of unique carbon compounds can form, including inorganic compounds (such as carbon dioxide and calcium carbonate) and organic compounds such as glucose, DNA, and polymers.

16

What are molecules made of and what are their properties?

Different combinations of atoms form all of the substances in the world. Atoms can combine to form molecules. Molecules can be made of atoms of the same element (an element) or they can be made from two or more atoms of different elements (a compound). Like atoms, molecules are too small to be seen and are in constant motion. When atoms are collected in large groups, they form crystals. The structure of a molecule determines the shape of crystals that the molecule forms.

17

How are compounds different from the elements from which they are formed?

Compounds are made from elements are made on a molecular structure with atoms

18


How can you predict how atoms will combine to form a molecule?

You can predict on how atoms will combine by the atoms that are combining

19

How can ionic compounds break into pieces?

Ionic compounds can break up, or “dissociate” into ions when placed in water. This forms a solution. Common ions are the hydrogen ion and the hydroxide ion.

20

How do chemical changes differ from physical changes?

During a physical change, the physical properties of a substance (such as size, shape, or state of matter) change, but the identity of the substance does not change. During a chemical change, one substance changes to a different substance with different physical and chemical properties.

21

What happens to atoms in substances when they undergo a chemical reaction?

Atoms change in their heat, mass, or change in substance. In a chemical reaction, bonds linking atoms in the starting substances (reactants) are broken allowing the atoms to rearrange to form new bonds. The results are new substances (products) that differ from the starting reactants.

22

What happens to the mass of the reactants in a chemical reaction?

During a chemical reaction, mass does not change. The total mass of the reactants equals the total mass of the products resulting from the reaction.

23

How does energy change during a chemical reaction?

In a chemical reaction, energy is absorbed or released. Endothermic reactions absorb energy. Exothermic reactions release energy.

24

What factors affect the rate of a chemical reaction?

Reaction rate is a measure of the speed of a reaction. Temperature, the concentration of reacting substances, and the surface area reactants all affect the speed of a reaction.

25

What is a chemical reaction?

A chemical reaction (also known as a chemical change) is a process in which one or more substances are changed to one or more new substances with new physical and chemical properties. In chemical reactions, chemical bonds are broken, atoms rearrange themselves, and new bonds form.

26

What are the signs that a chemical reaction has occurred?

A chemical reaction may be indicated by a change in color, odor, or temperature; the emission of light; and/or the production of a precipitate or gas bubbles.

27

What is the Law of Conservation of Mass?

The Law of Conservation of Mass states that matter is neither created nor destroyed in chemical reactions. In any chemical reaction, the total mass of the products always equals the total mass of the reactants.

28

How do scientists represent chemical reactions?

Scientists write chemical equations to represent chemical reactions. In a chemical equation, the reactants are shown on the left side, an arrow in the middle shows the direction of the reaction, and the products are shown on the right side

29

How are chemical equations written to show that mass is conserved?

Chemical equations are balanced to show that mass is conserved. The total number of atoms of each element is always the same on both sides of the equation. Coefficients are used with chemical formulas to balance chemical equations.