Question: "God's chosen people". Where might I find a description or mention of this topic in the Scripture?

Answer: "Chosen people" is a historic title applied by God himself to the nation (from one family) that He chose for himself out of all the nations... The Israelites (descendants of Abraham, Isaac and Jacob).

Deuteronomy 7:6-9

For you are a people holy to the LORD your God. The LORD your God has chosen you out of all the peoples on the face of the earth to be his people, his treasured possession. (7) The LORD did not set his affection on you and choose you because you were more numerous than other peoples, for you were the fewest of all peoples. (8) But it was because the LORD loved you and kept the oath he swore to your forefathers that he brought you out with a mighty hand and redeemed you from the land of slavery, from the power of Pharaoh king of Egypt. (9) Know therefore that the LORD your God is God; he is the faithful God, keeping his covenant of love to a thousand generations of those who love him and keep his commands. (NIV)

Read the passage in Psalms 105 about his special care of the Israelites, which ends...

Psalms 105:43-45

He brought out his people with rejoicing, his chosen ones with shouts of joy; (44) he gave them the lands of the nations, and they fell heir to what others had toiled for-- (45) that they might keep his precepts and observe his laws. Praise the LORD. (NIV)

In the New Testament, the salvation that came from Abraham's race -- through Jesus Christ -- expands the concept of "chosen people" to include not only Jews but also Gentiles who have found salvation in Christ. As grafted in branches (Romans 11:17-24), Gentile believers are also God's chosen people (Genesis 18:18, Galatians 3:8-9)...

1 Peter 2:9-10

But you are a chosen people, a royal priesthood, a holy nation, a people belonging to God, that you may declare the praises of him who called you out of darkness into his wonderful light. (10) Once you were not a people, but now you are the people of God; once you had not received mercy, but now you have received mercy. (NIV)

Check out Ephesians 1:4-6, 2 Thessalonians 2:13, and James 1:18 for some other New Testament verses regarding the people of God's choosing.